Shuts off while braking

[baddy3]

The truck shuts off while braking. I run fine before I fixed an oil leak where the fuel pump mounts to the block. I cleaned the tank, changed the fuel filter, changed rubber fuel hoses, cleaned the return line and the valve, and everything else I could think of. Also primed the system as per TM. The truck would shut off while idling and I slightly increased idle speed so it seems ok now. It only shuts off while braking, as it draws in some air once the brake is applied. Any thoughts? What should I check next, is vacuum somehow causing this?

 

[Ken_86gt]

The power brakes use engine power by the power steering system to work. Maybe the idle speed is still too low? I wonder why you had to raise the idle speed in the first place, maybe this might be the real problem.

 

[LanceRobson]

If the truck ran before working on the fuel system and will not run at the previous idle setting you have a problem in the fuel system. I would return the setting to where it was.

I suspect you have a restriction in fuel flow..

Then I would start by checking the troubleshooting guide in the -20 TM and be sure to check the electrical guide, too. Do you have a pressure tester you could use for fuel pressure?

Maybe removing the feed and supply lines and blowing low pressure air through them would help.

How did you clean the tank?

Lance

 

[jimm1009]

Blowing the line back to the tank can help but MAKE SURE that you remove the fuel cap first. Don't aks me how I know. Don't use more than about 15 to 20 psi though or you can blow the fuel lines in the flexible sections.
It wasn't a truck buy a helicopter but the same end scenerio.
They blew the whold side of the aircraft out.

Sounds liek a fuel restriction to me.

Once that is cleared up ensure that your timing marks are alighned.

There is a scribe mark onthe block and one on the pump that should match up.

A shop vac works well for the intial phase of bleeding fuel to the filter which you willl have to do since you are clearing the lines. If you tank is very low it may be a good time to remove it and physically check for crap in the bottom but think it through.
I did it the first time since you never know what Uncle had put in there. If you don't want to remove it right now there is a suction line on the tank to siphon water out if you want to try that. It is a hard line coming out of the tank and has a rubber cap on it. Remove the fuel cap and suck on it with air. You can use a varsol gun or simply rig a suction line. It is the same principle as a paint gun.

jimm1009

 

[BKubu]

Crazy as it sounds, it could be a clogged fuel filter. I had that happen once on an M1009. Under load, I guess the pump pulled enough fuel through. Coming down to idle, it would stall. I changed the filter and it went away.

 

[armytruck63]

I had exactly the same experience that Bruce had. My M1009 stalled when I let off the gas heading downhill towards a red light. Of course I lost power steering and power brakes. I got her re-fired and headed to the trusty auto parts store and bought a new fuel filter, which fixed the problem.

 

[baddy3]

Thanks for your replies. The filter is new just changed it and bled the system. Took off the IP cover, there was some crude there, but not much, the return valve is also clear and the glass ball moves freely. The alignment line is 1/12 off to the right, is that ok? I’m planning to disconnect the input line from the IP and blow it with compressed air and see if it makes any difference.

 

[1986Blazerk5]

Idle may still be too low

Im also wondering if a air leak would cause this?

 

[southdave]

I would say Filter is most likely,but check you return line you may need to clean the glass ball thingy

 

[baddy3]

Well, I blew out the fuel lines and cleaned the return valve again and the truck now runs great. It’s scary when it shuts off while driving, I could barely steer and use brakes, just can’t imagine it happening on a narrow downhill road. How would you guys stop the track in that situation?

 

[southdave]

Like this