dangrega33

Hi ya'll, I'm having some issues with my 95. I bought it in March and drove it home from Denver to New Mexico over mountains and into the valley. Just for reference, it was cooler outside, probably in the 50s or lower. I drove it home on the freeway the whole way with no problems at all! I even got 24 MPG! I was stoked. Anyways, I drove around on a warm day (80 degrees) for about 2 hours before turning around back home and on the freeway at 75 I noticed my truck started dropping in speed and stuttering really bad where the truck shook. It seemed to snap out of it and pick up speed for a split second and do it again. It keeps doing this. I make it home and change the fuel filter and I think all is good. Well, I hook up my small camper trailer 21' and about 5k lbs. I drive it south on the freeway (about 90 degree day) and I get about 20 miles before my truck does the same **** thing. I let off the throttle and my truck died. I pulled over and sat for about an hour making calls and then deciding to take off. I drive a good 10 miles more before it happens again. I make it home and take it in to a guy who looks at it and messes with it a bit. He takes it for a drive and can't reproduce the problem. I have since replace the lift pump, cleaned the fuel tank module and rigged my sending unit to work (could not find an aftermarket or oem unit). I tied up my FSS and drove my trailer around a little longer and it happened again and then again on my way home at a lower speed (40 mph) which I havent seen before. I put a fiel gauge and found I have 25 psi at idle. When I push the throttle about a quarter of the way, fuel pressure goes down to about 14 psi. I push about half to 3/4 and it starts going back up to about 24 psi. I never see a pressure higher than idle. I put a tork tek OFV and same thing... I am going to replace lines this weekend to see if I have an air leak somewhere and then I'm at a loss. I am worried that my problem isnt only low fuel pressure but could also be my injection pump? It really seems as if the stuttering happens when the truck is warm. I already tried tying up my FSS to make sure that wasnt dropping out and I had the same thing happen when it was tied up. Anybody point me in a direction? If the new fuel lines dont fix the problem, should i check anything else before dropping $500 to bench test the PPump? Or is this not a PPump problem? Again, this is a 95, which is a year that had PPump problems.. thank you so much guys!

oliver foster

That sounds like the P-pump is having problems when it gets hot. Yes that year pump is more prone to that problem.
The pump sounds like it might be ready for a replacement.
How many miles on the truck?
Manual shifted truck with the 175 HP pump I presume?

dangrega33

The truck has 155k miles and is all stock. Automatic tranny. This issue wont be related to the low fuel pressure?

oliver foster

You listed fuel pressure from 14-25 PSI that is enough pressure to make it run. You say it stumbles to a stop.
You listed that when it gets hot is when the issue happens. That make me think injection pump internal clearance issues.

You can try pinching off the rubber fuel return line with a small vise grip to see if it runs better for a SHORT test. The fuel pressure should bump up quite a bit.