After way too muchvtriuble, I have this solved. I
96 Tahoe 5.7L. Been down quite a while. Ran weak on fuel pressure, liked to die at stoplights any time I was below 1/4 tank. Then it just ceased starting after I reached my parking place. I did no diagnostics. Found a correct pump, Delphi. After changing this twice, getting high 20s on fuel pressure on Ign On Eng Off. Wondering what components would tell ECM to not send voltage to pump. Like a crankshaft position sensor or a TBI poppet on the injectors.
My crank is great and it wants to start. Going to swap relay off different 6.0L and re-test. Looking for obvious I may have skipped. I will hook up jumper wires and see how the ecm is getting sithe ot gnal from the ignition prime. Test the affected relays at trigger post.
I suspect issue is not the fuel pump or the wiring or the grounding, but in the electrical control side. I have a clean West coast vehicle and voltages were coming up very good. I have fresh fuel filter. Tank was spotless inside. Removed fuel filter was in perfect condition. Fuel is fresh.
Here is the solution. I just go lucky on stumbling onto it These cars are so hard to source parts for. I landed on the OEM type Delphi pump through Parts Geek. I did a lot of testing on it, and not sure if I caused first pump fail or if was a defect, but it had a short in the pump motor. Re-ordered a different Delphi with steel lines, but those lines had a down leg bend and would not fit the tank. I ordered another of the same Delphi pump as first one from Parts Geek. There just were no options, not rock auto, GM parts direct, etc... The pump that i could find was Chinese, or US reseller companies like Spectra (a grab bag of stuff).
This current pump is the Delphi that looks correct, has the original steel lines to compression couplings that mate to my new GM OEM steel lines for the rear section.
I called Delphi who I chosen so I could actually get support. They answered at 6:30 PM my time, I got to a tech support very fast. Provided my pump which by lookup was suppossed to be correct for 1996 (per Parts Geek) He tells me it is in fact a 25 psi pump made for Throttle Body (1995). I am getting exactly 25 psi when I tested this evening, in addition to doing one more 4 stage relay testing sequence. Car does exactly what it needs to. BCM sends signal. Voltage strong, Relay gets switch voltage on right steps. Tech support tells me I need a FG0084. I look it up as I talk and it is a plastic type I was trying to not order, but it does not have the steel lines, requires hose clamp fuel line connections. The right pump which starts 96 is a 62 psi pump, just like all the fact finding says.
I ask for a pump to use on my Delphi assembly that lets me stay in the wrong 95 unit with a 62 psi pump. That pump only part is FE0114. But it lets me keep my factory type housing and float, and steel lines.
The other part I battled over was replacing the fuel filler hose. Rockauto shows Dorman and Spectra (just resells various brands). I order the Dorman and is about 3" too short. Has to go back. No one in the entire industy has the right hose (via major brand stores). They all have the wrong 11" Dorman / Spectra. I find the correct one at Filler Neck Supply Co. It is a 15.25" long one. You have to shop the wrong application to find it. I stumbled onto that because my OEM hose has 4293 on it. D200A45R13R2.25 is their part but factory cross is 15644293. The lookup guide says it is for 92-99 Suburban, Tahoe, Yukon, Escalade.
I have bought tons of parts. This 2 door Tahoe makes me work very hard to find stuff that is correct.
