M1009 starting problem after short run

[alpine44]

After sitting for about four month, my M1009 started right up. However, after about 30 seconds the engine rpm increased slightly and then the engine stopped.

No more fire after that. Checked the fuel filter and verified that there is clean fuel coming to the IP. The shutoff solenoid clicks when the ignition is on and receives 12 Volt while cranking. But no fuel is coming out of one of the high pressure lines after loosening the nut at the pump.

Maybe there was an air bubble in the filter and the high pressure side is now vapor locked. Tomorrow, I will take the glow plugs out (to make cranking easier) and see whether I can get fuel out of the high pressure lines at the injectors.

I also read that a plugged return line can cause the IP to quit delivering. Is that correct and how do you troubleshoot that?

It looks like in order to troubleshoot the IP inlet, removal of the intake spider is necessary. Any tips for that?

 

[Barrman]

One of mine does that every so often. I have a small leak in one of the fuel lines between the lift pump and the IP. I have a spin on filter. I just haven't replaced all the hoses yet to get rid of the air inlet.

Mine will do as you describe. Fire up and run just fine for a few seconds. Then increase in rpm before turning off. I have found cranking while I count to 10, sit for a timed minute, crank while counting to 10, sit for another timed minute and if needed keep repeating will have everything working fine again. Mine normally comes back to full run after the 3rd or 4th crank time.

I don't drive the truck daily like I used to so I just haven't gotten around to messing with it. If you still have the stock fuel filter, that is a known leak source for many people. Try parking the truck nose down after you get it going again. The problem probably won't come back parked nose down.

 

[alpine44]

The problem was an air pocket in the fuel system.

I pulled the glow plugs, cracked the HP line fittings on the injectors and cranked the engine until diesel started dripping from the top of the injectors.

After tightening the line fittings and reinstalling the glowplugs, the engine runs great now. This was also a great opportunity to test all glowplugs and tighten up the electrical connectors.

Thanks for the helpful suggestions.

 

[sandcobra164]

Have you ever replaced or had the injection pump rebuilt on your truck? Mine started acting similar to yours when my injection pump was on it's way to failure. A quick way to check to see if your injection pump is on it's way out is to pull the fuel return check valve (technically referred to as a "Housing Pressure Control Valve"). There is a glass ball held seated by a small spring. It attempts to maintain a few psi of fuel pressure inside the pump. Normal pump failure occurs because the elastomer insert drive ring starts to disintegrate. This leaves small rubber like particles floating around in the low pressure side of the pump and tend to plug the fuel return check valve. If you're driving down the road and the truck randomly shuts off you can remove the glass ball with a small punch to remove the obstruction. A more thorough check would be to loosen the throttle cable assembly and remove the top cover of the injection pump to look for blackish particles. If you do end up finding them, I posted a pretty decent accounting of the steps involved in replacing the injection pump late last year.

 

[alpine44]

Have you ever replaced or had the injection pump rebuilt on your truck? Mine started acting similar to yours when my injection pump was on it's way to failure. A quick way to check to see if your injection pump is on it's way out is to pull the fuel return check valve (technically referred to as a "Housing Pressure Control Valve"). There is a glass ball held seated by a small spring. It attempts to maintain a few psi of fuel pressure inside the pump. Normal pump failure occurs because the elastomer insert drive ring starts to disintegrate. This leaves small rubber like particles floating around in the low pressure side of the pump and tend to plug the fuel return check valve. If you're driving down the road and the truck randomly shuts off you can remove the glass ball with a small punch to remove the obstruction. A more thorough check would be to loosen the throttle cable assembly and remove the top cover of the injection pump to look for blackish particles. If you do end up finding them, I posted a pretty decent accounting of the steps involved in replacing the injection pump late last year.

Hi there, Thanks for the info.

I found these two things online about the 6.2L fuel injection pump.

The first one is a GM video about the 6.2L engine that also covers the pump removal. (The military trucks do not have the secondary filter shown in the video)

And then there is this manual that describes, among other things, the complete teardown and rebuild of the pump.
According to the latter, the black debris clogging the ball valve comes from a deteriorating fly weight holder (page 4-57). Since water or alcohol is supposed to be the cause of the polyurethane retainer it would be a good idea not to use any fuel additives that contain alcohol.