Good morning,
I have dissasembled the tank filter tube and I do not have a filter at the end. Is this filter important?
I have blown air from the tank to before the pump. It was clean.
I have changed the piece of tube from the tank to the metal tube that goes to the pump.
I keep seeing air bubbles in clear tube before pump.
As soon as you start the engine, the pump pumps gasoline to the carburetor.
One question, does the tank cap have to be open or closed?
Thanks a lot
Elmer
Carburetor without fuel
Moderators: rickf, raymond, Mr. Recovery
Re: Carburetor without fuel
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Re: Carburetor without fuel
Ok, easy one first, yes the cap should be in the open position. Closed is only for fording. Now, that pickup tube is something that someone has manufactured and is not the right one. The original tube would go down and curve around so the pickup point, and filter, would be laying parallel to the bottom of the tank. Does that tube reach all the way to the bottom of the tank? and stay at least an eight inch off the bottom? If not you will run out of gas before you get to the bottom of the tank. You will definitely be picking up air as you drive. This is not a big deal until you start picking up a lot of air. But since that has been fabricated I would look at where that tube is brazed or soldered to the bottom of the fitting for leaks. Plug the tube on the outside and then fill the tube with the tube facing up with carb cleaner and see if you see any seeping out anywhere. Send a PM to csmith (memberlist.php?mode=viewprofile&u=753) and ask him if he has a pic of the pickup he changed out in his tank. He was the one I mentioned that had the leaking tube. Maybe if you see a pic of the original you can fab one up or Clell can tell you where he got his new one. If I were looking for one I would suggest Army Jeep Parts, or TJ Murray.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
-
ODRotorHead
- Sergeant
- Posts: 80
- Joined: December 5th, 2022, 11:30 pm
Re: Carburetor without fuel
A newbie’s perspective on the fuel system (newbie to newbie). In addition to the excellent advice you've already received, I hope there may be some small part of this post that will help you sort out your problem.
I have a new-to-me 1970 Ford A2 with a “pre-emission” fuel system, alternately referred to as a “non-emissions”system.
From the first time I started my MUTT engine, I experienced a series of performance and reliability issues that I suspected were related to the condition of both the fuel, and the fuel supply system. The engine would not start or idle without using some choke. Even with the engine at normal operating temperature, it stopped running abruptly as soon as I pushed the choke knob full in. Normal acceleration caused engine surging and loss of power. A slow, gradual acceleration allowed fairly normal engine operation up to about thirty-five miles per hour, but anything faster, or an uphill climb, resulted in a very rough running engine. The truck was unreliable and I couldn’t be sure I’d be able to make it back to my starting point.
There could be any number of different issues causing or contributing to the problem - worn ignition components, bad timing, low compression, valves out of adjustment, carburetor problems, etc., etc., but if the possibility of fuel issues isn't eliminated first, you may end up wasting a lot of time and effort going around in circles.
In this particular case, it was time to park the truck and do a thorough evaluation of the entire fuel system.
I can’t claim to be an expert on this topic, and I probably made a few mistakes along the way, but this is the process I followed. I’m hoping some of the real experts on this forum will identify my errors and provide better guidance.
Starting with the filler cap - there are two types, vented (11660517-1) and non-vented (MS53075-1). If I understand correctly, vented caps are for all the pre-emission systems, and non-vented caps are for systems equipped with emission controls. My MUTT had the wrong cap (non-vented) installed. Fortunately, that didn’t really matter because the seal was so badly cracked and deformed that it allowed plenty or air to pass.
Next, a look inside the tank. After pulling out the filler neck screen with a two-inch tear in it, I could only see the bottom of the tank. Not much to see other than all the rust flakes and grit covering the flat bottom. There wasn’t much fuel in the tank, but it had a brownish tint and a foul smell, so that issue had to be addressed before going any further. I used a small hand pump to start the fuel transfer and siphoned as much fuel as possible into a container (about four gallons). At that point, I unscrewed the drain plug and let the remaining liquid drain into a pan. I say “liquid,” because it was dark and viscous, and not anything I’d ever want to see in a fuel tank.
At that point, I put my skinny little arm down the filler neck to feel around so I could take measure of the amount of debris in the tank. The bottom felt gritty with lots of rust flakes sticking to my hand. Reaching a little farther in, the fuel pickup tube which extends to the bottom of the tank, is directly in line with the filler neck. Given what I’d already found, I can’t say I was entirely surprised to discover that the filter element was missing. All the grit and goo shifting around on the bottom of the tank was being sucked right up into the tube. Great.
The previous owner warned me that fuel gauge was operating erratically before I bought the truck. Fair enough. Since I was already fishing around inside the tank, I was able to turn my arm to the left just far enough to reach the float on the sending unit. Slowly moving the float up and down produced two readings: pegged to the left, or pegged to the right. Nothing in between.
Now, on to the top of the tank and the cover assembly. There must have been a problem at some earlier point in time because the space between the rim of the cover and the sides of the tank recess was packed full of white silicone sealer that looked like it had been applied with a rusty putty knife. All of the cover bolts were also slathered over with the same white sealer.
Just past the edge of the cover, all three fuel lines - supply, return, and vent - had been cut and patched with unmarked black hoses (gasoline/ethanol resistant?) and oversized, rusty screw clamps. Those were the only repairs to the return and vent lines, but the fuel supply line was also cut and patched with a length of hose across the front of the transmission cover. Bad enough already, but the end of the fuel hose that would normally have been screwed into the fuel pump had instead, been cut off. A hose barb and screw clamp were used instead. Less than ideal.
Looking more closely at the condition of the lines, there were just a few shreds of the old protective wrapping left on both the vent and return lines, but all three lines were misaligned, slightly kinked in multiple locations, and rusty under flaking paint. The fuel supply line on the passenger side had a section with significant pitting.
After pulling it off the hose barb, the ragged end of the fuel hose that had been connected to the fuel pump crumbled when I squeezed it. The hose on the return side looked okay, but a little bending pressure on that hose immediately revealed a significant amount of cracking.
The GI fuel filter had been removed and replaced with a larger, plastic unit (more hoses and rusty screw clamps). The filter didn’t contain any fuel (already a bad sign), but it contained fine sediment and was discolored showing a brown, “high tide” line.
The fuel pump was the only bright spot in the entire inspection. It looked relatively new, so I assumed it was in good condition. Unfortunately, that assumption would later prove to be false.
Lastly, the fuel pump vent line was missing and the vent was open to the elements.
So this is what I had so far . . .
• The wrong fuel cap with a bad seal
• A strainer element (filler screen) with a large tear in it.
• A system filled with old, nasty ethanol fuel that had gone through phase separation.
• A rusty fuel tank full of rust flakes and grit.
• A pickup tube missing its filter element.
• A malfunctioning fuel quantity sending unit.
• A fuel tank cover that may have been leaking under gobs of old silicone sealer.
• Fuel lines with multiple shabby “repairs,” kinks, and corrosion.
• Flexible hoses that were either cut off and crumbling, or cracked.
• A cheap, after market fuel filter.
• A missing fuel pump vent line.
All-in-all, the entire system was an unsightly and, more importantly, an unsafe mess. Given the overall condition of the system, I decided to tear it all out and start over. I ordered the required parts - a cap, filler neck screen, filter element for the pickup tube, fuel quantity sending unit, a complete set of new fuel and vent lines, two new fuel hoses, and a new filter.
While I waited for the parts, I removed the fuel system, including the tank. The only parts still attached to the vehicle were the fuel pump and the carburetor. Once I had the tank opened up, I could see that the interior was a rusty mess. At that point, I would have preferred to replace it with an NOS tank, but I couldn’t find one. If I had, I suspect it would have been way out of my price range anyway. Fortunately, I met some good people at the Weare Rally in July and they recommended that I try the POR-15 Tank Sealing System. I’d used something similar to seal a motorcycle tank about thirty years ago and had good results with that (I’m still riding that bike), so I decided to give it a try.
While I waited for the POR-15 to arrive, I ran an electrolysis process for a couple of days. It’s the first time I’d used electrolysis for rust mitigation and I was pleased with the result. I figure, if it’s worth doing, it’s worth over doing!
With regard to cleaning the tank, I did have one advantage that I wasn’t expecting. When I took the cover off the tank I discovered that someone had already cut out a section of the upper half of the tank baffle. I have no idea how, when, or why that was done, but it allowed me to reach all of the interior surfaces of the tank and do a thorough scrubbing with wire brushes and abrasive pads. I’m fairly confident I was able to remove all of the loose scale and most of the surface rust.
POR-15 application is pretty straight forward, but the instructions have to be followed closely. There are multiple ways to screw it up, so you have to plan ahead for each step. I won’t go into the details here, but I’ll be happy to share if anyone’s interested.
One thing that I will mention, is that the preparation steps require a lot of tank handling. I’m an old guy with a bad back, so slinging that tank around for a couple of hours wasn’t going to work for me. I had to find a reasonably safe work-around.
The solution was to hang the tank from a scaffold by attaching lines to all four corners. That allowed me to shake the tank in any orientation just by changing the lines. It also allowed me to position the tank in multiple orientations for the acid etching process without the risk of the tank falling off a set of saw horses and being damaged. Changing the lines multiple times was a bit tedious, but nothing compared to the pain of another ruptured disk!
Finally, the newly sealed tank was coated, cured, and ready to be reinstalled. New mounting hardware, a new cap, a new filler screen, a new filter element on the pickup tube, a new fuel quantity sending unit, and new gaskets for both the sending unit and the tank cover.
After reinstalling the tank and the new sending unit, I wanted to check to be sure the sending unit was working correctly. I flipped on the power and the fuel quantity needle pegged to the left side of the gauge. Hmmm. I reached in through the filler neck and gently moved the float up and down. No change. The needle remained pegged to the left. Not good.
There’s only one electrical connection to the fuel sending unit [28], so it has to be grounded to the tank through the mounting screws. I’d painted the top of the fuel sending unit, but I checked and there was clean metal-to-metal contact between the top of the unit and the base of the mounting screws. I pulled the sending unit out and put a jumper wire on it so I could check it while it was off the tank. With the unit grounded, it worked perfectly and the gauge functioned normally. Hmmm. That could only mean that, for some reason, the tank wasn’t grounded to the frame and that’s definitely not good.
I removed one of the four tank mounting bolts and dropped a star washer under the flat washer. Once I had the bolt tightened down again, I reinstalled the sending unit and everything operated normally. It turns out that I’d done such a thorough job of repainting the tank and the structure surrounding the tank that I’d inadvertently electrically isolated it. Note to self . . .
Next was the installation of the three hard lines. I bought a complete set of pre-formed lines from a well know MV parts supplier and hoped they would be both high quality and a good fit. I was pleased with the overall quality, and the fit was okay, but it could have been better. There will always be some variation between vehicles, so I didn’t expect a perfect fit, but in this case, two of the lines were too long so I had to cut and re-flare them. Once that was taken care of, everything came together nicely.
continued . . .
I have a new-to-me 1970 Ford A2 with a “pre-emission” fuel system, alternately referred to as a “non-emissions”system.
From the first time I started my MUTT engine, I experienced a series of performance and reliability issues that I suspected were related to the condition of both the fuel, and the fuel supply system. The engine would not start or idle without using some choke. Even with the engine at normal operating temperature, it stopped running abruptly as soon as I pushed the choke knob full in. Normal acceleration caused engine surging and loss of power. A slow, gradual acceleration allowed fairly normal engine operation up to about thirty-five miles per hour, but anything faster, or an uphill climb, resulted in a very rough running engine. The truck was unreliable and I couldn’t be sure I’d be able to make it back to my starting point.
There could be any number of different issues causing or contributing to the problem - worn ignition components, bad timing, low compression, valves out of adjustment, carburetor problems, etc., etc., but if the possibility of fuel issues isn't eliminated first, you may end up wasting a lot of time and effort going around in circles.
In this particular case, it was time to park the truck and do a thorough evaluation of the entire fuel system.
I can’t claim to be an expert on this topic, and I probably made a few mistakes along the way, but this is the process I followed. I’m hoping some of the real experts on this forum will identify my errors and provide better guidance.
Starting with the filler cap - there are two types, vented (11660517-1) and non-vented (MS53075-1). If I understand correctly, vented caps are for all the pre-emission systems, and non-vented caps are for systems equipped with emission controls. My MUTT had the wrong cap (non-vented) installed. Fortunately, that didn’t really matter because the seal was so badly cracked and deformed that it allowed plenty or air to pass.
Next, a look inside the tank. After pulling out the filler neck screen with a two-inch tear in it, I could only see the bottom of the tank. Not much to see other than all the rust flakes and grit covering the flat bottom. There wasn’t much fuel in the tank, but it had a brownish tint and a foul smell, so that issue had to be addressed before going any further. I used a small hand pump to start the fuel transfer and siphoned as much fuel as possible into a container (about four gallons). At that point, I unscrewed the drain plug and let the remaining liquid drain into a pan. I say “liquid,” because it was dark and viscous, and not anything I’d ever want to see in a fuel tank.
At that point, I put my skinny little arm down the filler neck to feel around so I could take measure of the amount of debris in the tank. The bottom felt gritty with lots of rust flakes sticking to my hand. Reaching a little farther in, the fuel pickup tube which extends to the bottom of the tank, is directly in line with the filler neck. Given what I’d already found, I can’t say I was entirely surprised to discover that the filter element was missing. All the grit and goo shifting around on the bottom of the tank was being sucked right up into the tube. Great.
The previous owner warned me that fuel gauge was operating erratically before I bought the truck. Fair enough. Since I was already fishing around inside the tank, I was able to turn my arm to the left just far enough to reach the float on the sending unit. Slowly moving the float up and down produced two readings: pegged to the left, or pegged to the right. Nothing in between.
Now, on to the top of the tank and the cover assembly. There must have been a problem at some earlier point in time because the space between the rim of the cover and the sides of the tank recess was packed full of white silicone sealer that looked like it had been applied with a rusty putty knife. All of the cover bolts were also slathered over with the same white sealer.
Just past the edge of the cover, all three fuel lines - supply, return, and vent - had been cut and patched with unmarked black hoses (gasoline/ethanol resistant?) and oversized, rusty screw clamps. Those were the only repairs to the return and vent lines, but the fuel supply line was also cut and patched with a length of hose across the front of the transmission cover. Bad enough already, but the end of the fuel hose that would normally have been screwed into the fuel pump had instead, been cut off. A hose barb and screw clamp were used instead. Less than ideal.
Looking more closely at the condition of the lines, there were just a few shreds of the old protective wrapping left on both the vent and return lines, but all three lines were misaligned, slightly kinked in multiple locations, and rusty under flaking paint. The fuel supply line on the passenger side had a section with significant pitting.
After pulling it off the hose barb, the ragged end of the fuel hose that had been connected to the fuel pump crumbled when I squeezed it. The hose on the return side looked okay, but a little bending pressure on that hose immediately revealed a significant amount of cracking.
The GI fuel filter had been removed and replaced with a larger, plastic unit (more hoses and rusty screw clamps). The filter didn’t contain any fuel (already a bad sign), but it contained fine sediment and was discolored showing a brown, “high tide” line.
The fuel pump was the only bright spot in the entire inspection. It looked relatively new, so I assumed it was in good condition. Unfortunately, that assumption would later prove to be false.
Lastly, the fuel pump vent line was missing and the vent was open to the elements.
So this is what I had so far . . .
• The wrong fuel cap with a bad seal
• A strainer element (filler screen) with a large tear in it.
• A system filled with old, nasty ethanol fuel that had gone through phase separation.
• A rusty fuel tank full of rust flakes and grit.
• A pickup tube missing its filter element.
• A malfunctioning fuel quantity sending unit.
• A fuel tank cover that may have been leaking under gobs of old silicone sealer.
• Fuel lines with multiple shabby “repairs,” kinks, and corrosion.
• Flexible hoses that were either cut off and crumbling, or cracked.
• A cheap, after market fuel filter.
• A missing fuel pump vent line.
All-in-all, the entire system was an unsightly and, more importantly, an unsafe mess. Given the overall condition of the system, I decided to tear it all out and start over. I ordered the required parts - a cap, filler neck screen, filter element for the pickup tube, fuel quantity sending unit, a complete set of new fuel and vent lines, two new fuel hoses, and a new filter.
While I waited for the parts, I removed the fuel system, including the tank. The only parts still attached to the vehicle were the fuel pump and the carburetor. Once I had the tank opened up, I could see that the interior was a rusty mess. At that point, I would have preferred to replace it with an NOS tank, but I couldn’t find one. If I had, I suspect it would have been way out of my price range anyway. Fortunately, I met some good people at the Weare Rally in July and they recommended that I try the POR-15 Tank Sealing System. I’d used something similar to seal a motorcycle tank about thirty years ago and had good results with that (I’m still riding that bike), so I decided to give it a try.
While I waited for the POR-15 to arrive, I ran an electrolysis process for a couple of days. It’s the first time I’d used electrolysis for rust mitigation and I was pleased with the result. I figure, if it’s worth doing, it’s worth over doing!
With regard to cleaning the tank, I did have one advantage that I wasn’t expecting. When I took the cover off the tank I discovered that someone had already cut out a section of the upper half of the tank baffle. I have no idea how, when, or why that was done, but it allowed me to reach all of the interior surfaces of the tank and do a thorough scrubbing with wire brushes and abrasive pads. I’m fairly confident I was able to remove all of the loose scale and most of the surface rust.
POR-15 application is pretty straight forward, but the instructions have to be followed closely. There are multiple ways to screw it up, so you have to plan ahead for each step. I won’t go into the details here, but I’ll be happy to share if anyone’s interested.
One thing that I will mention, is that the preparation steps require a lot of tank handling. I’m an old guy with a bad back, so slinging that tank around for a couple of hours wasn’t going to work for me. I had to find a reasonably safe work-around.
The solution was to hang the tank from a scaffold by attaching lines to all four corners. That allowed me to shake the tank in any orientation just by changing the lines. It also allowed me to position the tank in multiple orientations for the acid etching process without the risk of the tank falling off a set of saw horses and being damaged. Changing the lines multiple times was a bit tedious, but nothing compared to the pain of another ruptured disk!
Finally, the newly sealed tank was coated, cured, and ready to be reinstalled. New mounting hardware, a new cap, a new filler screen, a new filter element on the pickup tube, a new fuel quantity sending unit, and new gaskets for both the sending unit and the tank cover.
After reinstalling the tank and the new sending unit, I wanted to check to be sure the sending unit was working correctly. I flipped on the power and the fuel quantity needle pegged to the left side of the gauge. Hmmm. I reached in through the filler neck and gently moved the float up and down. No change. The needle remained pegged to the left. Not good.
There’s only one electrical connection to the fuel sending unit [28], so it has to be grounded to the tank through the mounting screws. I’d painted the top of the fuel sending unit, but I checked and there was clean metal-to-metal contact between the top of the unit and the base of the mounting screws. I pulled the sending unit out and put a jumper wire on it so I could check it while it was off the tank. With the unit grounded, it worked perfectly and the gauge functioned normally. Hmmm. That could only mean that, for some reason, the tank wasn’t grounded to the frame and that’s definitely not good.
I removed one of the four tank mounting bolts and dropped a star washer under the flat washer. Once I had the bolt tightened down again, I reinstalled the sending unit and everything operated normally. It turns out that I’d done such a thorough job of repainting the tank and the structure surrounding the tank that I’d inadvertently electrically isolated it. Note to self . . .
Next was the installation of the three hard lines. I bought a complete set of pre-formed lines from a well know MV parts supplier and hoped they would be both high quality and a good fit. I was pleased with the overall quality, and the fit was okay, but it could have been better. There will always be some variation between vehicles, so I didn’t expect a perfect fit, but in this case, two of the lines were too long so I had to cut and re-flare them. Once that was taken care of, everything came together nicely.
continued . . .
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-
ODRotorHead
- Sergeant
- Posts: 80
- Joined: December 5th, 2022, 11:30 pm
Re: Carburetor without fuel
continued . . .
Side note . . . For years, I’ve used those cheap flaring tools to mangle and mutilate any number of brake and fuel lines.
I haven’t had any line failures to date, but I still worry about earlier installations that may be susceptible to failure due to the deep gouges the flaring tool made in the walls of the tubes. I looked for an alternative and decided to give this mid-priced flaring tool a try:
It was a little pricy, but I have not been disappointed with the results. Done properly, flares are as close to “factory” as I could ever hope for, and the tubes are undamaged by the process. Unlike tubes chewed up by those cheap flaring tools, tubes, even coated tubes, show no tool marks.
I’ve read that some people have had difficulty getting fuel lines through the firewall on the driver’s side. I can’t speak to other models, but in my case, it was a simple matter of removing the two bolts that secure the accelerator pedal and moving that assembly up and out of the way. My “shop assistant” repositioned the pedal while I used both hands to align, rotate, and slide the lines through the firewall. It only took a few minutes and required very little cussin’. Hope that helps.
Time to fast forward. All the lines are in, the grommets replaced, hoses connected, filter installed, fittings taped and torqued, and all components secured.
In the hope of eliminating fuel as a variable, I dumped in five gallons of VP C-9. Straight gasoline (no ethanol) at 100 octane. A bit pricy, but I didn’t want to leave any doubt about fuel quality.
Side note - Five gallons brings the fuel level just up to the bottom edge of the fuel filler neck. Tank capacity is listed in the -10 as 17 gallons for non-emission vehicles (16 for emission control equipped).
After all that time, effort, and expense, and with building anticipation, I jumped into the driver’s seat, flipped the ignition on, pulled out the choke, and mashed down on the starter.
Crank, crank, crank. Nuthin’. What the _ _ _ _ ! ( Heck? )
Everything in the entire system (except the fuel pump) was brand-new and, to the best of my knowledge, in perfect condition. Why won’t this thing start?!?
The fuel pump should be self-priming, but I wondered if there might be so much air in the system that it might need a little help. I loosened the clamp on the fuel filter and unscrewed it from the carburetor. With the filter still in-line, I attached a short length of clear tubing to the threaded end of the filter and used that same small siphon pump to suck fresh, clean fuel through the line. Satisfied that there were no restrictions to flow (no kinks or clogs) and that the pump was now fully primed, I reattached the filter and tighten the hose clamp.
Back in the seat!
Crank, crank, crank. Nuthin’. What the _ _ _ _ ! ( definitely not “heck.”)
I’m sure the TM has a detailed trouble shooting procedure to follow, but the TM was on my desktop computer, so I decided to “wing” it. I unscrewed the filter and had my trusty “shop assistant” aim the end of the filter into a small container. Said shop assistant betrayed a measure of apprehension when I insisted she wear safety glasses, but she played along anyway.
Back in the seat, ignition switch OFF, I mashed the starter switch one more time. As the engine turned over, I was hoping to see fuel spurting from the filter at about 5 psi.
Crank, crank, crank. Nuthin’. Not even a dribble. Dang.
Having checked and rechecked every component and connection, and being reasonably confident that everything was in good order, the only remaining variable was the fuel pump itself. It was the only component that appeared “nearly new,” but hadn’t been checked. It was working before I started the project. Why wouldn’t it be working now?!?
With no other recourse available, I disconnected the fuel lines from the pump and removed it from the engine. On initial inspection, the case looked good, the rocker arm had zero play, and there was very little wear on the shoe. The only thing that was a little off was that the outer edge of the diaphragm appeared to be delaminated.
As a quick check, I used a short plastic tube to blow air through the inlet fitting (induction side) and out through the outlet fitting (delivery side). Fluids and gasses should pass through the pump in that direction (toward the carburetor), so that was a good result. Fluids and gasses should not pass through the pump in the opposite direction (toward the tank). When it did, I counted that as a fail.
In a general sense, there are three chambers in a mechanical fuel pump. At the top is the pump chamber where the diaphragm sucks fuel in through the inlet valve and pushes it out through the aptly named outlet valve. The second chamber, under the diaphragm is open to the atmosphere by way of the vent tube. Otherwise, it’s sealed from gasoline above by the diaphragm, and sealed from crankcase gasses below by the oil seal. The third chamber, below the oil seal. is open to the crankcase where the rocker arm extends through the mounting flange to make contact with the actuating cam.
Failure of either the inlet or the outlet valve will prevent proper pumping action and will allow fuel to drain down and back into the tank. Failure of the diaphragm will prevent proper pumping action and may allow fuel to leak and/or be pumped into the vented chamber below. Failure of the oil seal may allow crankcase gasses to enter the vented chamber above, and may even allow gasoline to pass through and down into the crankcase.
Some people are dismissive of the vent tube, but it’s an important part of the pumping system. Sealing the vent tube prevents a free exchange of air as the diaphragm oscillates up and down. This, in turn, results in inefficient operation of the pump and alternating pressures on the oil seal. In a worst case scenario this could contribute, over time, to a diaphragm rupture and fuel entering the chamber. Another way to look at it is to realize that the same volume of air is pumped in and out of the air chamber as gasoline is pumped through the pump chamber above.
Not installing a vent line to the air cleaner and leaving the vent tube open to the environment opens the possibility of water and debris entering and remaining in the chamber. Since the vent tube is near the top of the chamber, anything entering the chamber is unlikely to be expelled through normal air exchange during pump operation. Water and debris will settle in the bottom of the chamber around the oil seal and pull rod. That may result in accelerated wear and corrosion which may contribute to early failure.
Some may disagree, but it seems reasonable to assume the system was designed with a vent line up to the air cleaner for a reason.
Time for disassembly. It was unlikely that I’d be able to repair the pump, but it was important to know if it was in fact the point of failure, how it failed, and what may have caused, or contributed to the failure. I wanted to have the answers so I could avoid a repeat failure.
When the screws are removed to separate the pump halves, it’s best to unscrew them in an even pattern so the upper half lifts up evenly. The reason for that is to avoid elongating or even tearing the screw holes in the diaphragm. The diaphragm spring doesn’t have a lot of travel, so disassembly shouldn’t be difficult to manage.
Once you get it open, here are some things to look for:
Some pumps have replaceable components, but this cheap aftermarket pump isn’t worth repairing. In this specific case, there were several issues that, in combination, made me decide to replace the pump.
continued . . .
Side note . . . For years, I’ve used those cheap flaring tools to mangle and mutilate any number of brake and fuel lines.
I haven’t had any line failures to date, but I still worry about earlier installations that may be susceptible to failure due to the deep gouges the flaring tool made in the walls of the tubes. I looked for an alternative and decided to give this mid-priced flaring tool a try:
It was a little pricy, but I have not been disappointed with the results. Done properly, flares are as close to “factory” as I could ever hope for, and the tubes are undamaged by the process. Unlike tubes chewed up by those cheap flaring tools, tubes, even coated tubes, show no tool marks.
I’ve read that some people have had difficulty getting fuel lines through the firewall on the driver’s side. I can’t speak to other models, but in my case, it was a simple matter of removing the two bolts that secure the accelerator pedal and moving that assembly up and out of the way. My “shop assistant” repositioned the pedal while I used both hands to align, rotate, and slide the lines through the firewall. It only took a few minutes and required very little cussin’. Hope that helps.
Time to fast forward. All the lines are in, the grommets replaced, hoses connected, filter installed, fittings taped and torqued, and all components secured.
In the hope of eliminating fuel as a variable, I dumped in five gallons of VP C-9. Straight gasoline (no ethanol) at 100 octane. A bit pricy, but I didn’t want to leave any doubt about fuel quality.
Side note - Five gallons brings the fuel level just up to the bottom edge of the fuel filler neck. Tank capacity is listed in the -10 as 17 gallons for non-emission vehicles (16 for emission control equipped).
After all that time, effort, and expense, and with building anticipation, I jumped into the driver’s seat, flipped the ignition on, pulled out the choke, and mashed down on the starter.
Crank, crank, crank. Nuthin’. What the _ _ _ _ ! ( Heck? )
Everything in the entire system (except the fuel pump) was brand-new and, to the best of my knowledge, in perfect condition. Why won’t this thing start?!?
The fuel pump should be self-priming, but I wondered if there might be so much air in the system that it might need a little help. I loosened the clamp on the fuel filter and unscrewed it from the carburetor. With the filter still in-line, I attached a short length of clear tubing to the threaded end of the filter and used that same small siphon pump to suck fresh, clean fuel through the line. Satisfied that there were no restrictions to flow (no kinks or clogs) and that the pump was now fully primed, I reattached the filter and tighten the hose clamp.
Back in the seat!
Crank, crank, crank. Nuthin’. What the _ _ _ _ ! ( definitely not “heck.”)
I’m sure the TM has a detailed trouble shooting procedure to follow, but the TM was on my desktop computer, so I decided to “wing” it. I unscrewed the filter and had my trusty “shop assistant” aim the end of the filter into a small container. Said shop assistant betrayed a measure of apprehension when I insisted she wear safety glasses, but she played along anyway.
Back in the seat, ignition switch OFF, I mashed the starter switch one more time. As the engine turned over, I was hoping to see fuel spurting from the filter at about 5 psi.
Crank, crank, crank. Nuthin’. Not even a dribble. Dang.
Having checked and rechecked every component and connection, and being reasonably confident that everything was in good order, the only remaining variable was the fuel pump itself. It was the only component that appeared “nearly new,” but hadn’t been checked. It was working before I started the project. Why wouldn’t it be working now?!?
With no other recourse available, I disconnected the fuel lines from the pump and removed it from the engine. On initial inspection, the case looked good, the rocker arm had zero play, and there was very little wear on the shoe. The only thing that was a little off was that the outer edge of the diaphragm appeared to be delaminated.
As a quick check, I used a short plastic tube to blow air through the inlet fitting (induction side) and out through the outlet fitting (delivery side). Fluids and gasses should pass through the pump in that direction (toward the carburetor), so that was a good result. Fluids and gasses should not pass through the pump in the opposite direction (toward the tank). When it did, I counted that as a fail.
In a general sense, there are three chambers in a mechanical fuel pump. At the top is the pump chamber where the diaphragm sucks fuel in through the inlet valve and pushes it out through the aptly named outlet valve. The second chamber, under the diaphragm is open to the atmosphere by way of the vent tube. Otherwise, it’s sealed from gasoline above by the diaphragm, and sealed from crankcase gasses below by the oil seal. The third chamber, below the oil seal. is open to the crankcase where the rocker arm extends through the mounting flange to make contact with the actuating cam.
Failure of either the inlet or the outlet valve will prevent proper pumping action and will allow fuel to drain down and back into the tank. Failure of the diaphragm will prevent proper pumping action and may allow fuel to leak and/or be pumped into the vented chamber below. Failure of the oil seal may allow crankcase gasses to enter the vented chamber above, and may even allow gasoline to pass through and down into the crankcase.
Some people are dismissive of the vent tube, but it’s an important part of the pumping system. Sealing the vent tube prevents a free exchange of air as the diaphragm oscillates up and down. This, in turn, results in inefficient operation of the pump and alternating pressures on the oil seal. In a worst case scenario this could contribute, over time, to a diaphragm rupture and fuel entering the chamber. Another way to look at it is to realize that the same volume of air is pumped in and out of the air chamber as gasoline is pumped through the pump chamber above.
Not installing a vent line to the air cleaner and leaving the vent tube open to the environment opens the possibility of water and debris entering and remaining in the chamber. Since the vent tube is near the top of the chamber, anything entering the chamber is unlikely to be expelled through normal air exchange during pump operation. Water and debris will settle in the bottom of the chamber around the oil seal and pull rod. That may result in accelerated wear and corrosion which may contribute to early failure.
Some may disagree, but it seems reasonable to assume the system was designed with a vent line up to the air cleaner for a reason.
Time for disassembly. It was unlikely that I’d be able to repair the pump, but it was important to know if it was in fact the point of failure, how it failed, and what may have caused, or contributed to the failure. I wanted to have the answers so I could avoid a repeat failure.
When the screws are removed to separate the pump halves, it’s best to unscrew them in an even pattern so the upper half lifts up evenly. The reason for that is to avoid elongating or even tearing the screw holes in the diaphragm. The diaphragm spring doesn’t have a lot of travel, so disassembly shouldn’t be difficult to manage.
Once you get it open, here are some things to look for:
Some pumps have replaceable components, but this cheap aftermarket pump isn’t worth repairing. In this specific case, there were several issues that, in combination, made me decide to replace the pump.
continued . . .
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ODRotorHead
- Sergeant
- Posts: 80
- Joined: December 5th, 2022, 11:30 pm
Re: Carburetor without fuel
continued . . .
Rust was forming in the pump chamber and on both valve bodies. The rust I could see wasn't too bad, but the rust I couldn’t see was what concerned me most. If rust was forming on the mating surfaces of the valve seals it would lead to a slow reduction in pump performance which would eventually cause engine problems.
The diaphragm was distorted and delaminated, and appeared to have been damaged during earlier maintenance. The screw holes were elongated and small tears were developing.
Lifting the edge of the diaphragm and looking into the air chamber, both the diaphragm spring and pull rod were covered with rust. There was no evidence of a leak in the oil seal, but given the condition of the pull rod, I wouldn’t expect the seal to last much longer.
The most obvious cause of the pump failure/malfunction was the large flake of rust lodged in the inlet valve shown in the photo above. It was small enough to get under the valve seat, but too large to pass all the way through and into the pump chamber. It was easy enough to dislodge the rust flake with a small pick, and if I reinstalled it the pump may have worked reasonably well for a period of time, but I’d already decided that there were enough other issues to warrant the expense of a new pump.
Side note - If a filter element had been installed on the fuel pickup tube, that rust flake would never have been able to make its way up to the fuel pump. For want of a nail the shoe was lost, . . .
It took a few days to arrive, but the new pump went in without any issues. I unscrewed the filter as before and turned the engine over (ignition OFF) a few times. In a couple of seconds there were strong, steady spurts of fuel passing through the filter. Success. Once everything was screwed/clamped back together I started the engine.
It started quickly and ran smoothly. I could close the choke completely and, after a couple of minor idle mixture and speed adjustments, the engine idled smoothly too. After a thorough leak check of all the new fittings I took the truck out for a drive. The results on the road were equally satisfying. Significantly more power, no more hesitation, sputtering, stuttering, or stalling.
One thing I did change was the 90 degree inlet fitting on the fuel pump. Replacing it with a 45 degree fitting seems to provide a better angle for the fuel hose connection and more clearance for the dipstick:
There are lots of other potential problems such as vapor lock, fuel foaming, etc., but for the most part, fresh, high(er) octane fuel (the -10 calls for a minimum of 91), regular filter replacement, and good maintenance practices will go a long way toward increased reliability.
I hope others will correct any errors and provide better advice.
Now it’s time to change the oil in the gearbox and both differentials.
.
.
.
Rust was forming in the pump chamber and on both valve bodies. The rust I could see wasn't too bad, but the rust I couldn’t see was what concerned me most. If rust was forming on the mating surfaces of the valve seals it would lead to a slow reduction in pump performance which would eventually cause engine problems.
The diaphragm was distorted and delaminated, and appeared to have been damaged during earlier maintenance. The screw holes were elongated and small tears were developing.
Lifting the edge of the diaphragm and looking into the air chamber, both the diaphragm spring and pull rod were covered with rust. There was no evidence of a leak in the oil seal, but given the condition of the pull rod, I wouldn’t expect the seal to last much longer.
The most obvious cause of the pump failure/malfunction was the large flake of rust lodged in the inlet valve shown in the photo above. It was small enough to get under the valve seat, but too large to pass all the way through and into the pump chamber. It was easy enough to dislodge the rust flake with a small pick, and if I reinstalled it the pump may have worked reasonably well for a period of time, but I’d already decided that there were enough other issues to warrant the expense of a new pump.
Side note - If a filter element had been installed on the fuel pickup tube, that rust flake would never have been able to make its way up to the fuel pump. For want of a nail the shoe was lost, . . .
It took a few days to arrive, but the new pump went in without any issues. I unscrewed the filter as before and turned the engine over (ignition OFF) a few times. In a couple of seconds there were strong, steady spurts of fuel passing through the filter. Success. Once everything was screwed/clamped back together I started the engine.
It started quickly and ran smoothly. I could close the choke completely and, after a couple of minor idle mixture and speed adjustments, the engine idled smoothly too. After a thorough leak check of all the new fittings I took the truck out for a drive. The results on the road were equally satisfying. Significantly more power, no more hesitation, sputtering, stuttering, or stalling.
One thing I did change was the 90 degree inlet fitting on the fuel pump. Replacing it with a 45 degree fitting seems to provide a better angle for the fuel hose connection and more clearance for the dipstick:
There are lots of other potential problems such as vapor lock, fuel foaming, etc., but for the most part, fresh, high(er) octane fuel (the -10 calls for a minimum of 91), regular filter replacement, and good maintenance practices will go a long way toward increased reliability.
I hope others will correct any errors and provide better advice.
Now it’s time to change the oil in the gearbox and both differentials.
.
.
.
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ODRotorHead
- Sergeant
- Posts: 80
- Joined: December 5th, 2022, 11:30 pm
Re: Carburetor without fuel
This is the fuel fitting - 11681688 - for an A2 with emission controls:
This is the fuel filter - 11641033 - that goes with it:
Both are available at TNJ Murray, Army Jeep Parts, and a few others. If you're in Europe, you might want to check closer to home. You'll save a lot of time and money on shipping.
This is the fuel filter - 11641033 - that goes with it:
Both are available at TNJ Murray, Army Jeep Parts, and a few others. If you're in Europe, you might want to check closer to home. You'll save a lot of time and money on shipping.
You do not have the required permissions to view the files attached to this post.
Re: Carburetor without fuel
Fantastic write up!! and special thanks for the pic of the pic up tube, I did not have one to show him. Replacement tanks are pricey, and very hard to find. I have several I got in a deal where I bought out an inventory of parts and I will be selling them but I already had one guy turn me away due to the price of the tank and the A1 electric pump. Said he would go elsewhere. I wished him the best.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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svramselaar
- Major
- Posts: 1109
- Joined: December 30th, 2007, 6:48 am
- Location: holland
Re: Carburetor without fuel
hi
the intank filter is the same at a jeep cj
https://jeepmania.eu/en/fuel-filters/11 ... ep-cj.html
i think you can use a inline filter before the pump
it is easy to chance on the road or you must have little hands to go trow the filler pipe
george
the intank filter is the same at a jeep cj
https://jeepmania.eu/en/fuel-filters/11 ... ep-cj.html
i think you can use a inline filter before the pump
it is easy to chance on the road or you must have little hands to go trow the filler pipe
george
Re: Carburetor without fuel
In case it hasn't been posted yet, there is a pickup tube with filter on ebay. I believe it's the same place I got mine from this spring. When I pulled the tube out, all that was left of the filter was the plastic ring that attached to the metal tube 
M151A2 AMG
1952 M38A1 sold
1952 M38A1 sold
Re: Carburetor without fuel
I remember years ago, putting a metal encased fuel filter in the gas tank onto the pick up line, using a regular rubber fuel hose.I also had used the mutt in-tank fuel filter.
mark
1968 m274A5
1960 m151
1981 m151A2
1964 m416
1971 m416
1968 m274A5
1960 m151
1981 m151A2
1964 m416
1971 m416
Re: Carburetor without fuel
An exceptional writeup by ODRotorHead.
Useful Post Merit Badge - AWARDED!
Useful Post Merit Badge - AWARDED!
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ODRotorHead
- Sergeant
- Posts: 80
- Joined: December 5th, 2022, 11:30 pm
Re: Carburetor without fuel
I can't claim any authority on the subject, but I recently read that a fuel filter should never be placed on the induction side of the pump. The author stated that a filter on that side produces too much resistance to flow and significantly reduces pump efficiency. I remember the article because that's exactly what I was planning to do prior to reading it. I'm just guessing, but that may be why the engineers who designed the system put the filter on the pressure side (the pickup tube "filter" is really just a debris screen). Anyone know for certain?
While researching the "filter element" 11641033, I noticed that there are a lot of vintage vehicles that use very similar (or similar appearing) filters. I'd be surprised if the M151 filter element is unique to that vehicle. I'm hoping to do some research to see if I can find a readily available, new manufacture substitute. If I find one, I'll post the information. For FoxMike, do you have any idea what happened to your missing filter? Is it possible that ethanol, or fuel stabilizers/additives may have caused the filter screen to fail (dissolve?). Anyone else experience that kind of failure? Since the NOS filters were designed and manufactured before ethanol was introduced, we might want to look for a more modern, or an all-metal alternative.
While researching the "filter element" 11641033, I noticed that there are a lot of vintage vehicles that use very similar (or similar appearing) filters. I'd be surprised if the M151 filter element is unique to that vehicle. I'm hoping to do some research to see if I can find a readily available, new manufacture substitute. If I find one, I'll post the information. For FoxMike, do you have any idea what happened to your missing filter? Is it possible that ethanol, or fuel stabilizers/additives may have caused the filter screen to fail (dissolve?). Anyone else experience that kind of failure? Since the NOS filters were designed and manufactured before ethanol was introduced, we might want to look for a more modern, or an all-metal alternative.
Re: Carburetor without fuel
Those in tank filters tend to never get changed and his could very well have been original from the 70's They are plastic and as we all know plastic gets brittle with age. They simply break off. As far as putting a filter on the suction side of the pump, put your finger on that suction line and have someone crank the engine, you will find there is a LOT of suction there. A vacuum gauge well generally show 20 plus inches of vacuum on that suction side. That is a lot more force than the 3-4 lbs. on the pressure side of the pump. The pressure side is regulated by a spring and any restriction over that 3-4 lbs. with stop flow. There is no regulation on the suction side, that is straight camshaft action on the pump arm directly pushing the diaphragm up. I have also heard all the stories about filters on the suction side, and I have also seen all the damaged pumps from not having one. I have never, ever seen a filter on the suction cause an issue unless it was clogged solid and then it did exactly what it was supposed to do, prevent crap from going through. New filter solved that problem.
The original filter mounted right before the carb on the angled adapter is still available and it is also available in civilian form. I do not have the number off hand. But those filters are very small and will clog quite quickly. What I did on mine was run a drill bit through that original filter and clean out all the debris and reinstall it and then put a modern inline filter before that filter. It is bigger and works much better. If you are running an inline before the pump you can go with just that one, same effect, just different position.
The original filter mounted right before the carb on the angled adapter is still available and it is also available in civilian form. I do not have the number off hand. But those filters are very small and will clog quite quickly. What I did on mine was run a drill bit through that original filter and clean out all the debris and reinstall it and then put a modern inline filter before that filter. It is bigger and works much better. If you are running an inline before the pump you can go with just that one, same effect, just different position.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
Re: Carburetor without fuel
Some of you may remember the 'Farmer Bob Sock Filter' that was on my M151A2; literally a sock, over a soda can with holes punched in it and fashioned to fit over the pickup tube....and the darned thing obviously worked...until it didn't.
Go here to see the magnificence of making do - viewtopic.php?f=27&t=10252&hilit=waking ... &start=285
Google fuel pickup tube filter or fuel pickup screen and you'll find there are a lot of options out there.
And I still think the Waking Up A Texas M151 thread (though long dormant) is still pretty relevant for those who want to relate to doing a lot with a little.
Cheers,
TJ
Go here to see the magnificence of making do - viewtopic.php?f=27&t=10252&hilit=waking ... &start=285
Google fuel pickup tube filter or fuel pickup screen and you'll find there are a lot of options out there.
And I still think the Waking Up A Texas M151 thread (though long dormant) is still pretty relevant for those who want to relate to doing a lot with a little.
Cheers,
TJ
Re: Carburetor without fuel
I forgot all about that one. It's a shame a lot of these old threads fall by the wayside but at least they are still out there in their entirety. Try finding a post you made on the Facebook site from two days ago. Yea, that is just one of the reasons I do NOT do Facebook. Along with all of the really inaccurate info on there.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone