Might be PMD but seems like it isn't

[GMC-John]

When I bought my 1994 truck it was dead in the water so I installed a PMD relocation kit to behind the license plate. It started immediately and still starts in 3 seconds in 40 degree weather. Recently it started conking out when the engine returns to idle when in gear. I changed the PMD again but the problem was totally unchanged even though it feels like a PMD issue. I am wondering if the fuel shut-off valve is acting up since it just seems to run out of fuel. It usually starts in 30-90 seconds after these stalls if I floor it. Is there any way to prove that it is/isn't the fuel shut-off valve? The bolt holding the FSV in is tweeked a bit......maybe a clue? Do these become intermittent with time? My lift pump seems to be working perfectly.

[a5150nut]

Do you have any codes?

[Robyn]

A test you may want to try.....

With the engine idling.....open the water drain cock up on the front of the engine by the T STAT.
Put the hose in a can to keep the mess down

The engine should stay running and there should be a good stream of fuel into the can.
When was the last time the fuel filter was changed ???

If the engine stalls when you open the cock.....Lift pump is likely not running or is DEAD

Be sure the lift pump is running any time the engine is running.

Another thing to check is the oil pressure switch (Rear of engine behind the glow plug controller)
The Oil pressure switch has two functions....sends the signal to the gauge and a second switch inside operates the lift pump...
These can and do fail......

Check these out before spending time and money chasing the wind...

A fresh filter is not a bad idea.....and a new oil pressure switch is good PM too.

If the pump is bad replace it with a Delco if you can get one. The parts store brands are sketchy.....

**** NOTE****
After changing the filter....be sure to bleed the air out of the filter by running the lift pump to purge the air out.....

Just because the lift pump is making noise is not a sure bet.

What is the deal with the Fuel shutoff bolt TWEAKED ????
Unplug the shutoff and then turn the key on and then momentarily plug the shutoff back in...Should CLICK noticeably.

Low fuel pressure may be the issue..

Good luck