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Hi. I hope somebody can help me out.
I've been working on this all summer & can't figure out what to check next.
I've had my 1954 M37 for about 4 years. The first 2 years it ran like a top. I let it sit for 2 years then it wouldn't start. It would just crank. I got a rebuilt carb from Midwest Military and it started but would not idle without the choke on. It revs up fine but stalls out when it goes back to idle. I can get it to idle with the choke on just right but it stalls out at every stop sign. It always starts right back up. The idle screw does nothing. I can turn it all the way in or out. No difference.
The fuel pressure is between 3 & 4 psi at idle & when revved up. The timing is correct. New spark plugs. Coil is good. There are no vacuum leaks.
It seems like a fuel problem. Could the fuel pump be getting weak or did I get a bad rebuilt carb?

Hi Winston,

If it ran fine for 2 years it probably was a good rebuild. Sounds like a clogged idle circuit, which probably came from letting it sit for two years with fuel in it. If you have to pull the choke out it means there is too much air available for the fuel being supplied....…creating too lean a mixture to idle. You probably need to pull the carb and go thru the idle circuit to get any crud cleaned out.

Regards,
Bob

Usually when you have to use the choke to make it run without stalling it mean there is a vacuum leak somewhere. I had one that drove me nuts for a while . I found that the priming tube on the intake manifold were the cause. I removed them and used pipe plugs to close the openings. I found it by using a vacuum gauge and a can of Carb. cleaner.

Sal

Thanks guys.
The carb is a rebuild from midwest military. I got it a few months ago. It should be clean inside unless something went wrong.
Where is the priming tube. Is it under the intake manifold?

I should have said manual primer lines instead of tube. There are fittings in the side of the intake manifold as you face the side of motor with thin lines attached to them. See picture below. That's where I found my vacuum leak

. Sal

It turns out that the low speed circuit was blocked in my rebuilt carb. Never thought to check it.

Good find... I didn't even think of that..

Sal

In vehicles I drive seasonally, I use Stabil to try to avoid carb problems. I use it in my dirtbikes and M37 in the winter and my snowmobile in the summer. The Dodge is still occasionally driven, but the gas is not replaced nearly as often as it is in the summer months. If problems do occur, or to minimize gumming of the gas, does anyone recommend the use of additives such as fuel injector cleaners in the gas?

It has come to the place where gas quality is so poor that all the supplements are basically spending $$ on snake oil. Sta-bil has a new product out called Sta-bil 360. It makes a claim that it's much stronger than some other products, still too new to make a judgment call yet on that one. The best thing is not to let fuel sit in the tank more than 30 days, even that long is risky. What we do if sitting for even a few days is a must; turn off the cut-off valve that is near the fuel pump, let the engine run until it stalls. This pulls virtually all the gas out of the carb and fuel pump. You will sustain far less damage with these components stored dry. It is also a plus to only use traditional unleaded gasoline, without any ethanol blended in. We have 1 station in town that offers it, may be there is one near you too.

I checked online a while back, and there were no ethanol free stations near me. On my two stroke machines dirt bikes, snowmobile and chainsaws, I turn off the gas or drain it and run them until they stop. The premix gas sits in the tank until the next season six months later, and I have never had an issue in any of those machines. As far as the truck goes, it definitely sits longer than 30 days. If the carb gums up, can I return it to you Charles? On warrantee? You rebuilt it last in 2010

ZGjethro wrote:I checked online a while back, and there were no ethanol free stations near me. On my two stroke machines dirt bikes, snowmobile and chainsaws, I turn off the gas or drain it and run them until they stop. The premix gas sits in the tank until the next season six months later, and I have never had an issue in any of those machines. As far as the truck goes, it definitely sits longer than 30 days. If the carb gums up, can I return it to you Charles? On warrantee? You rebuilt it last in 2010

Honesty, doesn't matter who built it, the gum is only the lesser issue with this. Worse yet is the substance known as white rust, the powdery looking residue that coats everything. It attacks the tank interior surfaces, interior of the carb die cast housing parts, doesn't take long to totally ruin it. Sitting longer than 30 days, good bet you already have it growing.