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Hi all,
After reading in some thread here I thought I had my issue worked out and bought a replacement governor and installed it. However my issue is still happening. Anytime I am running uphill over about half throttle the engine will start stuttering badly and occasionally shoot a bit of fire out the tailpipe (with a nice report). It usually wont start until I am in fourth going up a long gradual incline at cruising speed. Once it starts the engine will keep pulsing until I let it idle for about ten seconds which usually requires me to pull over. On a flat or downhill road I can drive normally all day long. I can also drive up steep hills though I've never been on one for a long time while moving. I thought that it could be a float issue but I figured that would continue regardless of whether or not I'm moving.
The engine does not run rich normally as best as I can tell form the exhaust smell. I would best describe it as the ignition cutting or the choke closing over and over. Any insight would be appreciated.

Ben

Hi all,
I have been having an issue where my truck will begin stuttering above half throttle or so when climbing a slight hill. I have already replaced the governor as it seemed like the obvious culprit however that had no effect. The truck has no problem on flat roads, downhill, or even up steep hills (though I haven’t been on one for a long time). At first it would only happen at higher speed but it got considerably worse. Now once it starts the only thing to do is come to a complete stop and let it idle for a while. I recently replaced the fuel pump as well after it decided against pumping anymore though I think that was unrelated. I would say it was leaning out except it also shoots a fireball or two if I don’t get out of the throttle once it starts.Is it possible that it is just a float adjustment issue?

Thanks,
Ben

Sounds like a vacuum issue. Make sure your tank is properly vented. Check fuel DELIVERY from the pump. Not pressure, but flow. It really sounds like you are running out of fuel under load.

The reason I think that isn't the issue is that I can press the clutch in while the problem is at its worst and immediately rev the engine. As soon as there is a load it comes right back. How would I go about checking the flow?

Hi Ben,

Welcome to the site, I would double check your timing.

Bert

I've checked and adjusted the timing. It was about 4 degrees slow so that is fixed now. As far as fuel flow goes I decided to add a water separator and after starting the engine again it refilled the water separator and the filter in less that three seconds so I think that is fine. I think the next step is a carb rebuild most likely.

Ben,
Did you adjust the governor? They will do some pretty funny things if not set up properly. I drove one M37 that would accelerate hard, plant your head in the steering wheel, then accelerate hard again, then repeat until you were either unconscious or lifted off the throttle. When set up properly they work really well.

Did you re-check the float level? We had issues with that causing severe surging under a sustained load, much like a poorly adjusted governor. Bowl would drain and the float setting was so far off it would not allow the needle far enough off the seat to refill fully. Only happened under heavy load.

You may want to check out your ignition too. I've had both wires and caps that only started giving trouble under full load. On the bright side, the problems eventually got worse and were easier to diagnose . Interior of one of the wires failed and shorted to the steel braid and the cap suffered blow through at one of the towers.

Hope all this is helpful,

Andy

My situation sounds exactly like the first story you described. I have no idea how to adjust the governor so I'll look into that. The float is also on the list though I'm not looking forward to taking the whole contraption off again. This truck also has a civilian distributor with 12v ignition so that's a possible culprit as well. I should have a chance to work on it tomorrow evening so hopefully some progress will be made. Hopefully it will be able to make a few more trips out bar hopping before it gets to cold.

Ben,
Search up Charles Talbert's posts on governor adjustment. I think there's a scanned copy of the Carter instructions floating around too. It's actually pretty easy and if you go in small steps you should be able to see pretty quick if it's the governor. The adjustments can be done on the engine. In fact you can pull the governor cover on the engine to verify the starting measurements, but it's a bit annoying. Just go slow and record your changes.

As far as the float, leave the carb on the engine and pluck off the bowl's cover. Check the fuel level and float level. Adjust as required and use the bowl's drain and primer on the fuel pump to test your adjustment. This works well as you get a direct measurement of fuel level, not just a guess.

Hope this helps solve your issue!

Andy

It looks like the culprit was the float. I opened it up and it was closing about a half inch low. A bit a guess and check and everything looks good now. I took it for a couple of drives and it has great steady power and the governor kicks in around 45 mph. I'll probably leave the governor there since the truck is almost 70 years old after all. Thanks for all the help.

Ben,
Glad you're up and running well again .

Andy

Nice job; what a great informational thread; glad I never got anywhere as complex as this troubleshooting exercise-it would have driven me nuts!
Gary

So, another update:

The issue came back a day or two later and I was back to square one again. After it got a bit colder I started to see bubbles coming through the fuel filter. It seems there is a crack or leak in the line that got worse when it contracted from the cold. I picked up 15 feet of rubber hose and ran it to a gas can in the bed and everything is good to go. Now I just need to replace the tank (rust) and replace the lines.

I have followed this thread out of interest. My own truck seems to run fine, courtesy mostly to Charles Talbert and his shop. Months ago I completely re-did all my hard lines, brake, fuel, and vents.
Fuel lines were copper nickel from FedHill, where I also got new line connections, He did caution me that the line connections are not available from a US supplier, so to try to reuse my brass ones, which I did. Some of the foreign ones are drilled off center, and would be prone to leak. New hard lines from tank to engine via a Facet electrical pump. Cold weather can indeed induce leaks in hard lines. You can pull off the cover over the fuel tank, the oval one in the truck's bed, and see if you have any air leaks there where the hard lines connect to the in-tank fuel filter. Try to snug the connections up a bit, and perhaps check all the fuel line connections along the frame. Perhaps if the connections seem good, there might be still a small air leak. A short term solution might be to get fuel injection hose and run it from the tank to your fuel filter and pump. Some owners have run fuel injection line from tank to motor permanently, but others have cautioned about vacuum collapsing the line. If you decide to replace your hard fuel lines I can offer some suggestions. Not easy to make the proper double flare line ends, but FedHiill rents an otherwise expensive tool to make perfect flares. Good luck of course.

NV