M37 Carb

[wadefreedomvehicles]

SO I bought an Air Force M37 a few months ago. Seems like a great truck, very little to no rust.
The engine in it is painted red, it is 12 volt and all wiring is Civi.
It has a military carb and such on there though.
When I try to start it, the elbow for the air intake fills up with gas and I can't get spark. I have tried to adjust, but cant get anything.
I have thought about using this as a semi daily driver.
Should I rebuild the carb, or is there and alternative carb option for this that isn't too expensive?
Any help is much appreciated.

[Cal_Gary]

Check the carb float setting. If it's off just a wee bit it can overflow the intake tube.

You'll need a multimeter or test light to trace out your lack of spark-could be a number of things: cap, rotor, points, coil, ballast resistor (if equipped), etc.
Gary

[oros35]

Electric fuel pump?

I put on an electric pump and it was too much pressure and over took the float needle valve. Put a regulator in the line, dialed it back to about 3psi and all is good now.

[wadefreedomvehicles]

I did put an electric fuel pump on it, and then the mechanical fuel pump started working fine, so I disconnected the electric. I might need to just do some more tuning with the carb, but I don't really understand how to properly adjust it.

[RMS]

never seen a carb over fill and fill the intake elbow is your fuel pump sending gas into the elbow rather than the front of the carb ?

the only adjustment is idle mixture screw (a/f ratio) and idle speed. a easy way to check the the float level is to use the primer lever on the stock fule pump and see if you run out of action. if priming never stops pull the top off and check the level (described below)

over fueling is usually seen in the intake manifold by gas dripping from the douglas valve (pcv) tubes and fittings.

if you have the fuel line connected correctly with the float level set just below the throttle pump bore the check valve should hold up to 7psi (this can be checked with the top off). if it is squirting gas out of the breather tube in the top cap of the carb you could be missing a bearing and clip(or spring?) from the bottom of the throttle pump bore.....but gas would have to pass the plunger and piston to make its way to the breather and into the elbow ?????

on the electrical front

disconnect the power lead at the dizzy and confirm you have power. next check if the points are opening the right amount .018 to.020 clean the ground on the condenser, make sure its tight. confirm the correct combination of rotor and cap. some rotors are sprung with a button, others are ridged. some caps have sprung carbon, some caps have a solid carbon. sprung cap goes with solid rotor. there are also two sizes of caps and rotors for the civi 12v dizzys

if you have a 9v coil and a ceramic ballast resistor check for continuity... they are fragile

[Black Ops]

I've had this carb problem happen on a couple trucks, both times it was debris stuck in the needle valve.

[RMS]

and it drained back to the air cleaner elbow ? I got to pull up a diagram of the carb

[oros35]

Mine filled the air cleaner elbow just like mentioned above when the fuel PSI was too high. Was about 4 1/2 psi. Dialed it back to about 3 and seems good now. I adjusted it with the top off the carb. Needle valve was leaking by and stopped with the lower pressure. It was kind of like that spring on the needle valve was not strong enough or something. This is the first carb I've done that had a spring between the float and needle valve. Kinda threw me on that one.

I could hear the fuel squirting past the needle valve and I wondered where it was going. Pulled the plug at the bottom and out came all the fuel. Nothing went to the engine. It would run fine but as soon as you stopped (with the fuel pump still on), the fuel filled the elbow.

It is possible my float is set wrong, but I measured and to the best of my ability it appeared to be correct. I didn't make any changes to it from when I bought the truck (not saying the previous owner didn't screw it up but it didn't look like it had been touched in many years.)

[Kaegi]

it is totally flooded from trying to start with no spark. try cleaning the points with some sand paper or a points file. drain fuel out of elbow and check plugs. if plugs are totally soaked they might not dry out. do you know how to service points? if not maybe find someone who does. it speeds up the process of getting it running. Invest in a dwell meter if going to keep it points. I like the low cost and durability of points. if set up with a dwell meter they will last many 10s of 1000s of miles.

and we want pics of the truck!

[wadefreedomvehicles]

The electrical is all fine and works, I am just having problems with the carb. this is a fuel issue, not an electrical issue.
Thanks for your input though.
Maybe when it gets warmer I will go outside and work on it and mess with some of the stuff mentioned here.

[Kaegi]

you first post said no spark is why I mentioned the elec.

[wadefreedomvehicles]

By spark, I mean explosion, sorry, no combustion. I wrote that late at night after a long day. sorry, I should have clarified. My mistake.

[jim lee]

For setting your float level..

http://www.thingiverse.com/thing:1015269

-jim lee

[m-37Bruce]

For setting your float level..

http://www.thingiverse.com/thing:1015269

-jim lee

Hey Jim,
Did you make the gage ..er gauge, would it come with the rebuild kit?
Thanks,

[jim lee]

I made it.

-jim lee