MISFIRE on my A2

[linh79]

Hello,

I'm an absolut newbie for Ford Mutts, I own one since March 2019 and need some advices. Englisch is not my mother tongue

First when I got my Mutt, I just drive multi-times and some short rounds arround the block.
The cold start engine need 3 tries now before it runs (I also need some exercise for the start, before that I needed 5 tries) and when the engine is warm it need only one try.

In June, I made a bigger trip about 30-40km/18-25 miles.

After the first 8km/5miles and a longer up-hill pitch the exhaust begins to "blubble" like blob blob blob and after that sometimes there are misfire/backfire a la Harley Davidson and I lost speed power on the hill.

The weather was warm and approx max. 25°Celsius/77°F.

On the straight stretch there are no problems even when I give gas.
Only if I change the gears (2 to 3) and give gas at 15 miles/h the Mutt stutters at first (or blubbing/misfiring) and when it got speed there are no problems anymore.

I have the feeling I lost speed at 40 miles/h at that time, but I won't test more because of the misfire (safety first) and the car is new to me and I need to know it.

The last route was 2km up-hill with a higher pitch and again lost speed or sometimes misfiring.
After 1km I off the engine and make a break for down cooling.
When I started the engine again it runs directly!

Than when I got home for parking the Mutt backwards, there is a small down-hill and flat gateway to the garage, the engine goes off 3 times and 3 times it starts directly when I ignited it.

Any help are welcome!

Thank you in advance.

[Hambone]

If your fuel system is good, I would suspect coil.

[m3a1]

A lot of problems become far less noticeable at higher RPMs. Since you are staring with a vehicle that is new to you, I'd start with getting those valves adjusted and if you can manage it, also get a compression test. There are many things that could make your truck misbehave in this way but it is important to get a good baseline on the engine itself before going into all the peripheral things like ignition and fuel delivery. For example, if you have a cylinder in poor condition (but don't take the time to find out) no matter how much time and energy you spend making other things right, you'll still have problems.

if your truck is slow to start this may indicate an improper starting procedure on your part and/or perhaps a timing issue. A good, general rule for setting the timing is a two-finger width between he distributor housing and the oil filter. This will be very close to proper timing and a "good enough" setting to begin your work from.

Starting procedure when cold - Crank your truck over a few times with the ignition off. Then, switch ignition to ON, carburetor fully choked, gas pedal to the floor (no pumping of the gas pedal) and your hand on the choke, ready to gradually un-choke when the engine fires. Many people find that needing to use the choke has more to do with how much time has passed since the truck was last run rather than how warm or cold the engine is.

As for ignition faults, you haven't said anything about what kind of ignition you have. Electronic, or points? Have you examined the inside of your distributor? Things to physically check are: CAP - look for cracks or carbon scoring (the path of an errant arc within the cap), ROTOR (or chopper if you have electronic ignition) - should seat firmly upon the shaft without wobbling, SPARK ADVANCE mechanism - counterweights should move inward and outward freely, GENERAL CLEANLINESS - inside of the distributor housing should be free of oil, grease and debris and everything in its proper place.

Fuel delivery - it is my opinion that anyone who is serious about knowing what is going on with his or her truck should have a clear, in-line fuel filter. Being able to actually see the condition of the fuel that is being pumped up to your carburetor is going to tell you much about what is going on with your truck. If you don't have one, you should consider getting one.

We still have a ways to go, getting you sorted out. Look over the things I've mentioned and get back to us.

Cheers,
TJ

[rickf]

The very first thing to do on a 151 is a COMPLETE tune up. New plugs, cap, rotor and points if you have them. Then set the valves. Then set the timing at 6 degrees which it right on the timing mark. Do NOT listen to all the hot rod guys who will tell you it runs much better at 8 or 10 degrees, trust me, it does not. Make sure the weights in the distributor under the plate holding the ignition module are not broken and rusty. After ALL of that is the time to adjust the carburetor and not before.

[linh79]

Hello,

thank you for your reply.

It was quiet since I posted last time.
But I done some homeworks and I also made some researching for more infos and waiting for a date with a mechanic friend who looks over my shoulder.
Studing technical manuals, how, what and where I have to looking for.
Even things like which spare parts I have to buy if something is demaged. I prepare things before I open something at my Mutt.

Could you tell me how it should be:

1. valve clearance
2. engine compression

3. points converting into "Prestolite solid state ignition module" -> possible, without changing the cam, shaft assy and coupling, is that correct?
4. if you have originally points or "Prestolite solid state ignition module" inside and want to converting into "Swiss controls ignition module" (with larger rotor) -> I was told you have to change the cam, shaft assy and coupling, too, because it's not compatible, is that correct?



Regards

[m3a1]

I'm claiming expertise with ignition modules but I have had my hands on a few.

With regards to points vs ignition modules, DO keep your points ignition. Rick has said many times that he keeps a complete points distributor on hand in his kit, which is very good advice indeed. Now, when I say, "DO keep your points ignition" I'm not necessarily saying I'm a fan of points over electronic ignition. The balance between which is better is a very fine one and it really only comes down to personal opinion. We''ll all be sorry I wrote that because this sort of statement is often taken as an invitation to argue about the matter. No one ever wins the argument, by the way.

What I do is keep spares (and a lot of them) of what I regard to be generally consumable items and this includes ignition components. When it comes to Prestolite vs Swiss ignition (each has its own style rotor (or 'chopper' for the Swiss), they are a direct swap. Either will fit your distributor. Electronic ignitions can fail (failure runs the gamut between running intermittently, all the way to running not at all) and I have personal experience with an intermittent failure situation with a module, but the good news is, they are relatively inexpensive and take up very little space, making them easy to carry along with you when on an outing...which is not to say that they are unreliable but these trucks and their attendant parts are old and getting older by the minute so, having spares with you, and some basic tools, is a very good idea and these are really easy to install.

Points or electronic, every bit of this is dependent upon having a good coil. Having an original military coil is a huge bonus. Chinese coils (those that are chrome) have been much maligned for their poor quality though I suspect that many guys have been blaming Chinese coils for their troubles when they actually have been experiencing intermittent module failure. I am one of the few guys here who knows without a doubt that intermittent failure DOES happen.

Cheers,
TJ

[rickf]

TJ is one of the very few people I have ever seen that has had an intermittent module failure, both in the military vehicles and in civilian life. It is much more common that when they go they are gone mainly because, especially with the Prestolite, that the potting material that the electronic components are set in degrades and melts away and when that happens the electronic parts that are set so close together now have nothing to hold them and they short out. In his case he was lucky and the shorting parts did not go poof as they usually do. The coils are another issue, I have run a Chinese coil for several years with no problem but I know a guy that put one in and it exploded, literally! Many of the Chinese coils do not last one season. I keep two in my emergency kit. If you are going to switch to electronic then go with the Swiss controls but be aware that the original Swiss Controls units are no longer available and these have also been replaced with Chinese garbage. Keep a points distributor in your onboard parts kit.

[m3a1]

And for those who are wondering what intermittent module failure goes like, it goes something like this -

Truck will cold start without any difficulties and will run as well as any other while the overall engine temps are low. But after a while, the truck will run a bit balky (and what is happening here is the spark is beginning to weaken as the heat and resistance rises within the module). It may even stall and restart but there comes a point where the truck will not restart and no amount of tinkering will cause it to restart. During this period, the truck (and the electronics within the module) are cooling down. When that cooling process is sufficient the truck will restart. I did not run my defective module to it's ultimate failure.

So, how did I come to this diagnosis? I did a heck of a lot of checking here, there and everywhere on my truck. I went through every possibility and those who followed along with my postings during that period will attest that I uncovered a LOT of sketchy stuff on my truck as I tried to track this problem down. Why did I check everything BUT the module? Well, at the time, conventional wisdom shared here dictated that a module either worked or did not work.... which in my circumstances was something that did not turn out to be entirely accurate. We live and learn here on the 838, sometimes through the experiences of others.

What I am trying to impart to you really has nothing to do with the trust you should or should not place in either type of ignition system and it sounds like you are trying to figure that out. Both were used extensively and IMHO, both are trustworthy. If it came down to the matter of the ease of having to replace the guts of the ignition alongside the road or on some trail somewhere, I would prefer to have to replace the electronic ignition because there are no points to have to fiddle with and under adverse conditions (particularly for those who are inexperienced or unprepared) points can be daunting, whereas electronic ignition is as close as you can get to plug and play.

I hope you found this information useful.

Cheers,
TJ