Famous Fuel Pressure

[OBS_Trash]

I came across a couple YT videos of fuel pump stuff, 2 references state anything below 55psi will give issues. Mine is 50# running. Anyone else have 50# and no issues?

 

[Schurkey]

1996 - 5.7 350

I’ve replaced every GD thing aside from the Fuel pump,(EGR.FuelFilter.MAF, Plugs.Wires.Rotor.Cap.Ignition Coil.IAC.CrankShaftposition sensor.EngineCoolant Temp, New Fuel spider Injection assembly with new Fp Regulator

2 references state anything below 55psi will give issues. Mine is 50# running. Anyone else have 50# and no issues?

WHICH spider assembly did you install? OEM poppet-injector or the upgraded electronic injector?

The electronic injector spider is less-sensitive to lower fuel pressure (within reason.)

 

[OBS_Trash]

WHICH spider assembly did you install? OEM poppet-injector or the upgraded electronic injector?

The electronic injector spider is less-sensitive to lower fuel pressure (within reason.)

OEM Poppet, which includes new fuel pressure regulator too (just for others that may not realize that reading this thread)

 

[Schurkey]

OEM Poppet

Too bad.

 

[Komet]

I came across a couple YT videos of fuel pump stuff, 2 references state anything below 55psi will give issues. Mine is 50# running. Anyone else have 50# and no issues?

Is that with idle vacuum or no vacuum?

 

[OBS_Trash]

Is that with idle vacuum or no vacuum?

Well, that’s me driving it around the block with the gauge laying on my windshield.

I’m going with…..Idle?

 

[OBS_Trash]

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“Quick Diagnosis is a 97’ Chevy with Fuel Pressure Problems” by ScannerDanner

Hands down the best Fuel Pressure troubleshooting video I come across.

Appreciate all the feedback Fam! After watching this video with the other info I’ve had, I don’t think I’m going to get a confirmation on a solid running 5.7 At 50# of pressure. This would be the 3rd time 55# and up is what is required has been referenced. I’ll still test the voltage, but pretty sure it needs a pump. Which was my original thought, the shop I brought it to said the pump was good, that sent me down the road of sensors. Once I change it, if that repairs it I’ll post what pressure it runs after the pump for future reference and maybe help someone out down the road.

I really was amazed at how many videos I watched where the video starts with pressure issues (40’s 50’s, none, different issues) on a gauge. They replace the pump in the video, and then it shows them driving or running it and it’s great. Not one video of post repair pressure. Thought that was interesting

 

[tinfoil_hat]

Well, that’s me driving it around the block with the gauge laying on my windshield.

I’m going with…..Idle?

Well there you go. Did you even read the previous replies? The test is conducted with the engine off, key on.
Watch for the initial spike, then make note of the pressure after it leaks down for a few seconds. Go get the Chilton manual for your truck. It covers all this stuff.
Your soot out the tail pipe is not being caused by your fuel pressure.

 

[dharg]

WHICH spider assembly did you install? OEM poppet-injector or the upgraded electronic injector?

The electronic injector spider is less-sensitive to lower fuel pressure (within reason.)

I've had 4 of these GMT400's. They all have fuel pump problems, even if you use Delfi or Delco fuel pumps. They will not start with less than 50lbs. The pumps always seem to pump enough volume but lack pressure. I have cured every one of them by copying a "Ford" idea. Leave the pump in the tank and add an inline pump from a mid 80's F150 302 to the frame. Tou have to make a bracket, mount usually somewhere before fuel filter. Add after market relay that triggers off original fuel pump relay to run new pump. Also leave original relay hooked up so that tank pump just becomes feeder pump to new pump. By doing so all safety protocalls are in effect such as shutting of when engine dies incase rollover etc.. It will start and run better.

 

[L31MaxExpress]

I've had 4 of these GMT400's. They all have fuel pump problems, even if you use Delfi or Delco fuel pumps. They will not start with less than 50lbs. The pumps always seem to pump enough volume but lack pressure. I have cured every one of them by copying a "Ford" idea. Leave the pump in the tank and add an inline pump from a mid 80's F150 302 to the frame. Tou have to make a bracket, mount usually somewhere before fuel filter. Add after market relay that triggers off original fuel pump relay to run new pump. Also leave original relay hooked up so that tank pump just becomes feeder pump to new pump. By doing so all safety protocalls are in effect such as shutting of when engine dies incase rollover etc.. It will start and run better.

I have had a half dozen of them. No issues with the in-tank pumps. I have also used the OE Vortec factory replacement pumps on a TBI sending unit is a couple of 3rd gen F-cars, an Astro van and both G20 vans. On the GMT400s and similar like my 97 Express and 99 Tahoe, I use a Racetronix harness to power the pump directly from the alternator output stud. The Racetronix harness has the updated 4 wire flat connector and I upgrade the bulkhead connector and wiring on the sending unit as well.