I recently purchased a 1986 military CUCV and when i trailered it home i let it run for about 30 minutes and shut it off. It refired a couple times and i left it running for a couple of minutes while i ran inside, and when i came back out it had died. I could not get it refired for anything, i tried using a very small shot of ether (even though its a no no) and jumpstarting it, but nothing has worked. It runs fine when it is running, but what would cause it to die all of a sudden? It has done this several times now where it'll run for several minutes and then it will just die. Should i change the fuel filters? What all does this require? Thanks in advance, Sticks

Sounds like a fuel supply problem. If history is unknown, change the fuel filter, check for good fuel flow to the filter first, then check for fuel flow through the injection pump, (remove rubber line from top of injection pump, fuel return,) route it in to an open container. Fuel should come out of this line while cranking or running. If no fuel is coming out, check fuel shut off solenoid, (located under top of injection pump) listen for click, when key is turned on and off, or remove pink wire from injection pump with key on and listen for click. If no fuel is getting to the filter, check the fuel tank switching valve.:grd:

I know that it is getting a good fuel flow to the filter, but the filter probably does need to be changed. What steps do i follow in order to change the filter and prime the system in order to prevent air from entering the fuel system? It is almost like an electrical issue is causing the engine to shut off because it doesnt sputter like it is running out of fuel, it just dies all of a sudden like i turned the key off or something.

Could be the shutoff solenoid inside the pump then.

My suggestion, have the pump rebuilt since its basically history unknown.

But thats coming from a guy who builds them everyday ;)

Sticks96, I have a 1986 M1028 which has/had the same problem. I found that the water drain cock on the bottom of the fuel filter assembly was leaking, drawing air. The problem is that our ff assembly is different than the cilivan model. I could not find the packing/hard rubber seal that the water drain cock seals against. So I removed it, very carefully, by using a wood screw as an extractor, then putting the seal overnight in silicone, it seemed to help no more air leak, however I have to use my foot as the cold start soleniod. I guess I should change it out or check the little wire that seems to break off! This might be your electrical problem...

As to bleeding the air out of the system after a filter change you have to make an air lock, this can be done by using a bottle (750ml glass whiskey bottle) slightly filled with fuel, then a clear plastic/nalgene line inserted over the air bleed valve on top of the ff assembly with the other end placed inside the bottle below the fuel level. Crack the air vavle enought to release the seal, you'll see bubbles. Remove the pink wire from the injection pump and crank the motor for no more then 10-15 secs. Our 24volt starters are expensive and create a tremendous amount of heat so allow it to cool for 2 mins between bleedings. Do this 2'x make sure the line stays below the fuel level, then close the air bleed valve, remove the line, replace pink wire to IP. It should start.

My fuel shut off solenoid died and so did the truck while I was entering the freeway! I pushed her back off the on ramp, you should purchase one of these and keep it in your truck along with a starter replay and glow plug relay. And of course your tool kit w/bleeder setup and a few gallons of fuel!!

Hope this helps. Greg PS Hey Cam whats a fuel tank switching valve? And someday I'll do a Cummins/M1028 its just the best combo GRH

I have a 1986 M1028 which has/had the same problem. I found that the water drain cock on the bottom of the fuel filter assembly was leaking, drawing air.
GRH, at best, you could have found a fuel leak, but the filter base is pressurized, it can't draw air there while the engine is running unless your supply pump was a no count.

Did the truck leak while it was parked overnight? Its possible that you might have had fuel draining out of the filter base while the truck was off, but it would have leaked like crazy if this were the case.

A fuel tank switching valve is for dual tanks. This shouldn't be the problem as the CUCV's never came with duals that I know of. Although, someone could have added one after the fact I suppose.

A common problem with the military filter setup is said to be a fuel pressure switch on the bottom of the filter housing. It is alleged that it will let air into the system when the truck is not running and cause all sorts of problems. Common thing on the mil-veh list is to change this switch before trying to diagnose any further.

TDG, I guess I wasn't clear. Yes the truck lost its pressure overnight, it was not leaking like crazy just a few drops it has stopped since I siliconed the packing overnight and rebuilt the FF assembly with new seals and o rings.