fuel problem

[kenisret]

95 6.5 TD auto 2wd vin f
stumbling under accel. no trouble codes hard to start after start will shut off on its own and then hard to start.Replaced lift pump,fuel filter and fuel pump relay.While eng is running opened filter bleed valve and no fuel flow also noticed when rep. filter very little fuel in filter bowl.Also no press at bleed valve on therm. housing.Plugged in spare FSD and no help.Any more ideas. Thanks

[gmctd]

Oil Pressure Switch powers the lift pump - you could also have a dirty sock - no, not yours, the one in the fuel tank - that filter is affectionately known as 'the sock'

[Robyn]

have a helper work with you.
Place tranny in D with safety brake set.
Open the bleed valve and place the hose in a can. Have the helper turn the key to the start position with tranny still in D
The starter will not (should not) work but the lift pump should run.
If the pump works and fuel comes out of the hose good then the pump and the "SOCK" are fine. Restart the truck and make sure the lift pump is working. If not then its the Oil pressure switch that is most likely gone south.
It could be the Fuel pump relay in the electrical box on the drivers side of the engine bay too.

Hope this helps

Robyn

[kenisret]

With eng off shifter in drive hold key to start and fuel flows from filter bleed valve and fuel drain valve at therm. housing.Start eng and idling there is no fuel flow from filter bleed or from drain hose.Eng is idling normal.What the heck is going on?

[Robyn]

To make life easy you have either a bad Oil pressurre switch or the fuel pump relay is bad.
Replace both and you should be fine.

The oil pressure switch is behind the drivers side head on the block.
Not handy but a can do job.
The relay is in the little black plastic electrical box on the drivers side by the ABS system. (The lid to the box should have a sticker in it that tells what is what in there)

The relay and the OPS are available at most parts stores.
The reason you get the stumbles and it will restart is that on the start circuit the lift pump is working and on the run side the OPS is not completing the circuit and the lift pump is not running so the IP transfer pump is trying to do all the work and it was never designed to do that.

Good luck and let us know

[kenisret]

Robyn,
Just a heads up on my problem.I replaced the oil press sw and that did the trick.Thanks for the assist. Ken