931A2 Intermittant starting, starts and runs for a while then stops.

[sspanzerss]

Four years ago I purchased a M-931A2, drove it approx. 375 miles home no problems, shut it off. Two days later tried to start, wouldn't start, installed new lift pump and it fired right up. The truck has sat for about 2 1/2 yrs, I put batteries into it, it fired right up and ran for about 5 minutes then quit, I bled the fuel system from the screw next to the small fuel filter and the screw on the injector pump, still wouldn't start. I installed new fuel filters and made a fuel cap with a air pressure gauge and a tire valve stem to put air into the fuel tanks, one of the rubber lines on the fuel selector valve was leaking fuel after I had put air pressure to the fuel system. I removed the fuel selector valve and cleaned it out and installed new O-rings and 6 new hoses on the valve, installed a new lift pump and replaced the fuel supply line from the lift pump to the bulk head fitting on the frame. I bled the fuel system and it fired right up, it sat overnight and I tried it in the morning and it fired right up, but I only let it run for about 1 minute to make sure it started, I shut it off and tried starting it about a half hour later, wouldn't start. I had to bleed the fuel system again and then it started right back up. Batteries are good, fuel tanks are full and fuel is clean. Is there a check valve in the fuel system that I am missing or in the Injection Pump that may be bad. I just can't figure it out, what am I missing!!! It is not an electrical issue only a fuel.....

 

[86m1028]

There is a return fuel check valve in the fitting on the IP.
You have a leak some where, I just went thru this on an m936a2.

I believe there is a check valve on the lift pump also.

 

[73m819]

I would guess the o-rings in the selector valve dried up and now suck air

 

[Jericho]

Don't forget to to check the fuel solenoid, Ie, is it pulling on start.

 

[wreckerman893]

I would guess the o-rings in the selector valve dried up and now suck air

The M36A2 I babysat for so long had this problem. It will drive you nuts. You could run the crane all day long at about 1300 RPM but if you took it out on the road and ran it wide open it would eventually start sucking wind and die. If you pulled over and let it idle for a while you could limp home (if you were close to home). After you shut it down and let it sit a day or so it would crank up and you could run the crane as I described. Grimlims are a booger.

 

[topo]

If this truck has aeroquip or a rubber type fuel line the thin inside liner in the fuel line may have separated from the outside and is collapsing and blocking the fuel . When the truck is off it opens back up and closes off again when it has fuel being pulled through it .