Startup stumble

[brianMo]

Truck seems to start fine but stumbles and dies if I let it sit more than a couple of days. I get white smoke and then it is hard to start until I bleed the injectors. I thought it could be an injector but have changed all 6.
It will run for about 15 seconds before it dies. Air leak some where? If I run the truck every day it seem to be alright. It does not like to sit idle. Any help would be appreciated.

 

[DavidC]

Sounds like an air leak. Next start just bump the starter and listen for the lift pump, can you hear it running ?. It should run for about 30 seconds after the bump. I had a problem similar and found the lift pump not running. There is a large elect plug on the drivers side with a lot of wires, I partially cycled that plug with out totally unplugging. That was 2 years ago and still working. I take it you do not have a fuel pressure gauge that would tell you a lot. The gauge is pretty much a requirement on a 2nd gen with a VP injection pump.

 

[brianMo]

I do have a gauge and yesterday I bumped the starter and it came up to pressure. It seemed a bit slow though. I have a new fuel filter on order, but it has only been 4-5k miles since I changed. Started fine but stumbled when it reached I think an air pocket. I was thinking about getting a new lift pump with larger fuel line. It acts like when you change a fuel filter.

 

[JR]

Most definitely sounds like an air leak as David mentioned. They can be a real pain to track down depending on the severity, and if yours starts after sitting for a night it sounds like a slow one. If your using the original fuel lines it would be a good idea to replace with larger anyhow, the ID of the OEM lines are very restrictive. If your lift pump is still mounted on the engine block it would also be a good time to relocate it to the frame rail. Less heat and vibration and the pump is pushing rather than pulling as pumps are designed to do. All fluid dynamic basics, and why they were retrofitted by Dodge a few years down the road.

 

[DavidC]

Check the "T" at the back of the block drivers side where the vp, return from the back of the head (from injectors) and the return to the tank for any signs of leakage. The overflow on the vp may not be closing all the way, make sure all the banjo bolts are tight including the one on the back of the head if you can even get to it. This can be a real pain to find as it could include the o rings on the tubes to the injectors and various other places. Also check the fuel canister nut, I think 10 inch lbs and canister drain.

 

[DavidC]

If you should move the lift pump be sure to install a relay and have the original wires fire the coil only, then run a seperate fused 12vdc through the contacts to the relocated pump.

 

[BoeingDiesel]

The return line and tee connection at the back of the block is an essential check to narrow the field and real dog to access but can be done with a little perseverance. Just a thought...have you verified voltage to the lift pump with it running?

 

[brianMo]

Found my problem. It was simple. Leaking from the fuel canister. Simply tighten nut. Thanks

 

[DavidC]

Well that was easy. A lot better than the alternative.