Went to town this morning ran fine then i came home. couple hours later i started it up ran for a min. then stalled. pulled the water/fuel filter out and it was empty turned it over with the filter out still no fuel motor has 186,000mi. on it. what do you guys think?

Thank you very much
Diezel

Could be the oil pressure switch or the lift pump but the truck should still run with both of those bad. The IP should still suck fuel from the tank unless it is worn to much. Maybe someone else that has had this problem can point you in another direction.

It is probably good for you to DO the diagnostic checklist.

I know it is not the most popular things to do but it has helped a lot of people diagnose their problem

Pay particular attention to the Lift Pump thread.

I would hook up lift pump direct temporarily and take out the fuel filter and look for gushing fuel. MAKE SURE TO SEPARATE THE FACTORY WIRING AWAY FROM YOUR DIRECT WIRING OR YOU WILL BLOW AN ECM FUSE IN THE BLACK BOX UNDER HOOD DRIVER'S SIDE.

If you have fuel (check just to be sure) and there is a gurgling inside that housing, you are sucking air or out of fuel. Lines before lift pump are a problem (or even the tank assembly).

Then replace filter and check for a geyser at the filter **** (on the filter).

If all is Ok but the Oil Pressure Switch is bad, the lift pump will not work.

i did some experimenting and i filled the fuel bowl up (w/Fuel) and tried starting it and when fuel got to the cylinders it ran. so im thinking that i have a bad lift pump what do you guys think?

Thank you
Diezel

I think you should do the check list to eliminate some of the Parameters associated with the lack of fuel. It will help you and us to narrow down the problem.


http://www.dieselplace.com/forum/showthread.php?t=42248

Might be OPS Might be air Might be lift pump

Oil Pressure switch ONLY operates the lift pump on OBD1 trucks (94-95) ALL later than that the PCM runs the supply pump via a relay under the hood in the fuse panel. So most likely its the pump itself.

WOW I learn something everyday--thanks TDG I stand corrected.

Oil Pressure switch ONLY operates the lift pump on OBD1 trucks (94-95) ALL later than that the PCM runs the supply pump via a relay under the hood in the fuse panel. So most likely its the pump itself.
Is it?
I thought that on 96+, while you're on Wait to start cycle - engine off-, the LP is fed by the PCM, and as soon as you key on and run the engine, the PCM gives place to the OPS wich then feed the LP---

Be sure to see if you're leaking fuel ONCE you check for LP operation. My pick-up tubes on my sending unit were toasted enough to allow enough air into fuel system to cause a stall and no restart condition.

My crappy gravel driveway concealed my problem for a while!:D

Further to T.D.G,s post,info from Turbine Doc & Gmctd indicate that as well as the computer running the lift pump ,( including run mode) the ops circuit is still wired in, in a parallel fashion . I guess the word is " redundant" wiring. If one circuit fails pump should still get power through remaining circuit.

Be sure to see if you're leaking fuel ONCE you check for LP operation. My pick-up tubes on my sending unit were toasted enough to allow enough air into fuel system to cause a stall and no restart condition.

My crappy gravel driveway concealed my problem for a while!:D


And on a related note, the tank sock (also on the sending unit) could be clogged.

I had empty bowl one time and I traced it to leaks on the rear side of the pump (front side would leak). I found bubbles under load between filter and IP but I think it is from the filter. I think I will get rid of this filter element as it leaks with some filters (Purolator bad filter seals).


I installed a clear 1/4" tube today (small engine rated fuel line) from the filter to the IP running up and over the Plenum and back down so I can see the fuel floe in the driver's seat when cranking. I do have bubbled on high rpm, which I did not know. This is very helpful in many ways. I am also installing one in the rear from the tank to the lift pump to check supply (I have dump PKP and tank is accessible).