M37 Difficult starting after sitting a week.

[Charlie 6]

My M37 idles and runs great, problem is if it sits a week it cranks but does not start right away, I can crank it for about 20 times before it starts. Once it starts it starts up first try every time after that and the following days. After a week of sitting it takes alot of cranking. The guy before me had the carb rebuilt, gas is new and there is no hand crank on the fuel pump. Any ideas besides driving it every day, LOL!

 

[mkcoen]

Any ideas besides driving it every day, LOL!

Starting it every day?

Or at least more than once a week?

Sorry, that's about as "expert" an answer as I can provide.

 

[vtdeucedriver]

Fuel leak somewhere? How many days before it does this? If you drove it Friday and then again on Sunday, it's ok? I would think it could be many issues at this point.

 

[Bill W]

Fuel leak as mentioned by VT and/or could be weak check valves in fuel pump causing fuel to drain back to tank, to check for this turn off the fuel valve at the pump when your done running it for the week or try using the primer on the fuel pump before starting it next time after sitting ( if the lever is still there ). I installed a elec primer pump on my 37 as it would sit weeks at a time.

 

[1958 M274]

My Dad's M37 and my WC-51 (which uses the same 230 engine and Carter Ball and Ball carb) have been two of our most reliable vehicles to always start easily, even after sitting for several weeks.

I suspect that you have a problem with your carburetor. Even if the check valves in your fuel pump were leaking and letting the fuel flow down out of the line and pump, after sitting for a week or even a few weeks, there should be enough fuel in the carburetor bowl for it to start and run.

Also, are you sure that your choke is closing all the way?

Good luck!
Joe

 

[Charlie 6]

There is no fuel leaking any where. The fuel pump does not have a handle, I wish it did. The fuel pump I believe is fairly new, it has a glass bowl next to it, and there is fuel in it. I will check the choke this weekend. Maybe the guy that rebuilt the carb did something incorrectly during the rebuild process. Any more ideas will be appreciated.

 

[M543A2]

Take the inlet fuel line off the pump. Hold your finger over the inlet hole in the pump while someone cranks the motor to see if you feel a good vacuum there. If you do not, the pump has a valve problem. Do you have a filter before the pump? On older vehicles like this it is a good idea because the fuel tanks are usually not clean. The filter catches particles before they can get into the pump valves and cause them to not seal properly. If the pump body has screws around the periphery, you can take the pump apart and clean the valves and any other crud out of it that might be present. As a precaution, I would also take an air hose and blow back through the tank to pump line to clear any crud there that might be impeding fuel flow somewhat.
As to the comment that even if the pump valves are letting fuel drain back to tank there should be enough in the carb to start it after sitting a week or so, I find that if mine has run long enough to get up to temp, when shut off the fuel can get percolated out of the carb and also can evaporate over time. It would be a really good idea to source a proper pump with a priming lever. I find I have to prime mine at times because it invariably will sit for longer than the week you mention!
Regards Marti

 

[stampy]

I figure the fuel is draining back to the tank. I have a jeep that has done this also. Easy fix is a boat primer or and electric primer pump. Or you can search and find why it is draining back which is the correct long term solution.

 

[Kasper31]

I had the same problem, I corrected the problem by installing an electric (24vdc) fuel pump next to the fuel tank.
It is turned on by a switch on the dash to build up fuel pressure then turned off. I also installed a fuel filter at the same time next to the electric pump, to remove any dirt and water. Even on real hot days when some will vapor lock I can still start it by running the electric pump a short time.

You cant wear it out looking at it, use it, if it breaks you found your limit........

 

[Bill W]

I had the same problem, I corrected the problem by installing an electric (24vdc) fuel pump next to the fuel tank.
It is turned on by a switch on the dash to build up fuel pressure then turned off. I also installed a fuel filter at the same time next to the electric pump, to remove any dirt and water. Even on real hot days when some will vapor lock I can still start it by running the electric pump a short time.

I had mine on a duel switch one was "Momentary" for priming the other was "On" which helped when she started to vapor lock

 

[Charlie 6]

Definitely looking into adding an electric fuel pump to assist in start ups. Thanks for tips.

 

[Oldfart]

It depends to a degree on which fuel filter your truck has. The filter on the fire wall has rubber hoses that tend to crack and bleed air. If you install an electric pump back at the tank the leaks will show up when you pump up the lines. The cracked hoses allow air to suck into the fuel pump and vapor lock on warm days. When shut off, the fuel can back sphion to the tank even if the fuel pump check valve is working OK. Same thing for the rubber hose before the fuel pump.

 

[Kasper31]

Oldfart you are correct ! ! ! I had assumed that his fuel system was / is in good condition and could take the
fuel pressure that the electric fuel pump would build up. The standard fuel filter had been removed from my truck
before I purchased it. Thanks again for bringing this safety item up. Everyone should check their hoses now and then.

 

[Oldfart]

Oldfart you are correct ! ! ! I had assumed that his fuel system was / is in good condition and could take the
fuel pressure that the electric fuel pump would build up. The standard fuel filter had been removed from my truck
before I purchased it. Thanks again for bringing this safety item up. Everyone should check their hoses now and then.

I discovered these things about my own M37 when I installed an electric fuel pump to overcome vapor lock some 45 years ago. The intank filter has fewer rubber hoses to worry about.

 

[Charlie 6]

Learning alot from you guys, when I went in the army the M37 was already phased out, we had the M880, M151A1/2, M1008, M561. Thanks. Working late this week so I'll be working on my M37 saturday.

 

[Bill W]

I discovered these things about my own M37 when I installed an electric fuel pump to overcome vapor lock some 45 years ago. The intank filter has fewer rubber hoses to worry about.

Yes the 37's with intank fuel filter ( around 1953 and newer ) have only one rubber hose which is the 8" long one ( with valve ) that runs from the frame to the intake side of fuel pump, the rest is all metal pipe. Of course the intank fuel filter is worthless as far as servicing it if it gets clogged which is why I took mine out and installed a spinon filter under the truck

 

[zak]

There is also a fuel priming system that came on some of these trucks. I thought I saw a picture of it in the TM's but now I can't find it. A priming pump was mounted in the dash near the drivers door with lines to the intake manifold. A few pushes on the priming handle squirts raw gas into the manifold and your good to go. After my truck sits for long periods ( it seems like a lot lately ) it will start right up.

 

[Oldfart]

Yes, the fuel priming system was discontinued early on and was removed or disconected in the field on almost all of the vehicles that came equiped with the system.

 

[ranger.41]

Charlie 6,
If you have a civilian power wagon pump, that was rebuilt by and sold by Carquest, have seen them fail. The correct fuel pump has the primer lever on the front. Also fuel with ethanol can do a number on diaphrams. I purchased my rebuild kit from Then and Now Automotive. I rebuilt my fuel pump 4 years ago with their kit.
ranger.41

 

[98taco3]

Had the same issue with my truck but it happened much faster. Figured out the civilian power wagon fuel pump didnt have enough oomph to suck fuel from the tank. If you look at the size difference of the diaphrams is quite apparent why this is. The military pump is at least twice the size of the civvy one. Installed an electric pump and have had no issues cept when it sat for a very long time. Just didnt want to start but was because of low compression...