fuel pump? not priming

[99prixgt]

The car is a 97 gtp. The fuel pump will not turn on with the key turned. I tried doing a fuel pump re-wire and see if that would fix it. the fuel pump and regulator have been replaced, along with a fuel pump back in april. I think just the pump was not replaced and not the entire assembly. I seem to be getting voltage to the pigtail that connects into the fuel pump (2.5 volts out of the prong with the black wire, the battery was dying on the car)

I was going to do the "high speed" mod, but on this 97 there isn't a relay for it. I also tested the fuel pump relay, which seems to be working since, i swapped one in from my other car. I never hear the fuel pump prime but if the car sits all night, i can start the car and drive it without issue at all (even though i never hear the pump turn on) then when i turn it off and try to re-start the car it cranks but no start

i was thinking these, im trying to rule out the following...


cam position sensor
crank position sensor
fuel pump assembly unit
bad pcm

does anyone know if the cam and/or crank position sensor have to do anything with tripping current to the fuel pump?

[CTKGP09]

by high speed mod you mean bypassing the resistor?

the crank sensor only cuts spark IIRC

[99prixgt]

by high speed mod you mean bypassing the resistor?

the crank sensor only cuts spark IIRC

yes, but on my 97 there isn't a low/hi speed relay, which i thought was odd. I almost think that in 97 there was only a hi speed only, just like on gt's

thanks, i can rule out crank sensor

[BoostJunki3]

.....sounds like issues i had when my fuel pump was dying.....

[99prixgt]

the only thing is, is that the fuel pump was just replaced back in april. I just want to be sure its the fuel pump, i don't know maybe it needs a whole new assembly. Im going to try and re-wire the whole fuel pump sending wire from the pcm to the fuse box relay.

[blueguy]

Pumps tend to randomly take ****s like that...do you run the tank low before filling it up? Running low on gas makes the pump work harder...therefore cutting pump life. One brand you REALLY want to stray from is the AutoZone Airetex or whatever that crap is...worst brand on the market for any car.

[99prixgt]

Pumps tend to randomly take ****s like that...do you run the tank low before filling it up? Running low on gas makes the pump work harder...therefore cutting pump life. One brand you REALLY want to stray from is the AutoZone Airetex or whatever that crap is...worst brand on the market for any car.

oh, hey buddy . That's a good question, I'm not sure how the previous owner ran the car. Judging by all the part receipts, he likes awfulzone. The previous owner had replaced the pressure regulator, and resistor (which again is weird because this particular 97 doesn't have a resistor relay, just the fuel pump relay.)

Would any fuel pump assembly work with this gtp? I know the gtp has a ventri port but, if i didn't care about that, would a gtp/gs/gt/ls/ss fuel pump assembly work?

[99prixgt]

does anyone know which wire on the fuel pump pig tail is supposed to be getting voltage?

[CTKGP09]

im sure the member with user name 'mikey' can get you a schematic, since he seems to have endless GM schematics at his expense

[99prixgt]

I have a schmatic since i have all 3 volumes of the gm service manuals

Supposedly there is a ground coming off the fuel pump pigtail somewhere, i guess this would be the next step.

I got a chilton manual when i bought the car, its really worthless

[CTKGP09]

wow, service manual FAIL i guess...

[99prixgt]

wow, service manual FAIL i guess...

? how so

these manuals are like reading though playboy

[99prixgt]

ok well, i tested for continuity on the grounds of the pigtail plug that leads into the fusebox. I have sound to both grounds, one is a pcm ground and the other is a fuel pump ground. Also i get power to the plug when i turn the key to the on position, the last wire on the pig tail is a sender, i have a signal there as well. im 99% sure the fuel pump itself failed. Im going to order a whole new pump assembly and see how it goes.

[CTKGP09]

sounds good, looks like your on the right path. hope that solves everything

[99prixgt]

i just installed a fuel pump from the w-bodystore. The pump primed right away, drove the car around a while with re-starts often, pump is priming perfectly and the car is running good. I went to re-flash the pcm for some trans settings, went to turn the key and fuel pump didn't turn on and car stalled. Waited a while, and re-flashed the computer with origional bin, still no fuel pump priming. Waited a little and then the fuel pump primed and car started. Right from there we went and got gas, turned the car off filled up with some more gas, car was previously hitting 1/4 tank, still no priming. Waited a little bit then it primed and car started. We got home, then i turned the key back and 4th about 10 times and every time the fuel pump primed.

I didn't hook up the fuel pump re-wire, im going to try that tomorrow.

I'm starting to think its a bad pcm. Any other signs i should get with a bad pcm?

On another note, if the car is running and you open the door, sometimes the light will go on then off like the door was closed, with the door still open and the car still running

could it be something with the ignition column, causing all of this?

[99prixgt]

ok, today i wired up the zzp fuel pump re-wire kit. Car started rough but the fuel pump was priming, the car stalled when i reved it a little but, i don't think it was the fuel pump since it was still on. I cleaned the maf and it seems to be good. I drove around for 2 1/2 hours (start, re-start, drive, repeat) the car didn't stall once, and the car was running good, i goosed it a bunch of times. I still think it could be a bad pcm. I'm gonna get a good replacement and take it from there.

[99prixgt]

I don't know if anyone is following this thread but, I haven't replaced the pcm yet, the car has been running awesome since the fuel pump re-wire and new fuel pump, almost 170 miles so far without issue (keeping my fingers crossed)

another couple of things i have done were...

-replaced the iridium plugs for autolite 605's (i don't know why you would ever use iridium's in a L67 car)
-cleaned MAF
-Replaced honeycomb (old one was real ****ed up)
-Made an open cone intake
-180* t-stat

[QwikGT]

could have been the factory fuel pump wire taking a crap the car is 14 years old

[shawngtp]

sounds like a combo of things went or going bad. Seems like you got it hammered out though. I was reading and thinking the same thing on the pcm too. Good to know