How do you check the pump? Can you put 12v to the gray wire coming out of the tank with it disconnected from the plug where it goes into the bottom of the car? Will this make the pump come on if it is good? Will it need a ground to come on? I just changed my pump and it still will not come on. Already verified good relay and fuse. I just want to hear the pump come on before I go chasing other possibillities, I think that the VATS works by disabling the fuel pump. I'm wondering if this could be the proplem. Thanks for any input or ideas, I dont know what to do next.

 

besides just spinning the pump has to develope and maintain preassure. you'd need it to run and check it with a gauge.

 

Did you check the ecm/fuel pump fuse in the engine bay? It should be on the pass side by the radiator. I think it's a 10 amp fuse in a fuse holder. Also VATS disables the starter and injectors, not your fuel pump so you can rule that out. You can apply 12 volts directly to the pump as you stated, but if it's a new pump I have the feeling it's still good.

 

I checked the fuse by the radiator and changed the relay on the firewall. It is a brand new Walbro fuelpump. I had just finished installing a cam, headers, new injectors and a few other things, got the exhaust hooked up and drove the car to work and home. The next day on the way to work the car died like it ran out of gas, which it was extremely low and I was going to stop for some but did not make it. When it still would not start after putting gas in it, I splashed some in the throttle body and it ran long enough to burn what was in there, I then realized that I was not hearing the fuel pump come on. So I checked the fuse and replaced the relay and finally the pump itself. One more thing, I ignorantly did not have an o2 bung welded onto my header, so when I did drive it to work it was running rich as hell due to no oxygen sensor. Although I dont see how that could have anything to do with the problem I am having now. I already have the wiring harness and stuff for a heated sensor to fix that. The guy next door who has an 89 Camaro swears it has something to do with the VATS and claims his car did the same thing and he somehow bypassed the system or something and says he can do the same with mine, I am not one for rigging things on my car and would rather fix it right even if it costs more money. Sorry for the novel, but I HAVE to get this car going.

 

When you first turn the key to 'on' does it at least kick on for 2 seconds? If you're positive you can't hear it and you're not getting pressure at all, the only thing I can think of is the wiring between the relay and the pump. You can try to isolate it by checking for 12v at the gray pump connector with it disconnected...you might need longer leads or another person for this because you should see 12v for a couple of seconds if it works right. If it works, then you can assume it's wiring aft of the gray connector going to the pump.

 

It doesnt come on at all. Do you think a diagnostic machine could pinpoint it?

 

Is there something with the oil sending unit that will keep the fuel pump from coming on? Like a safety thing to keep it from starting if the oil is too low? I know it has plenty of oil, but maybe the thing is malfunctioning.

 

This question has surfaced several times before. If you study the schematic of the fuel pump power system, you'll discover that the auxilliary oil pressure switch is NOT a safety shut-off for the fuel pump. It is simply a redundant, parallel path for power to the pump in the event the pump relay fails.

Yes, a diagnostic would pinpoint the problem, but connecting the car to a Tech1 or other diagnostic device won't. Your diagnosis will require a voltmeter, diagram, and some time.

Incidentally, the Fuel Pump/ ECM fuse on your GTA is on the left (driver's) side of the engine compartment, near the battery, and it should be a 20A. Camaros have the fuse on the right side, since the battery is on opposite sides for each model.

The ECM should energize teh pump relay for two seconds when the ignition is first turned on. To repeat the cycle, turn off the ignition for at least 20 seconds, then turn it on again.

 

Thanks for pointing that out...i'm thinking of my Camaro again.


I just happen to be looking at a wiring diagram and it shows a green/white wire from the fuel pump relay control from inside the ecm to the fuel pump relay is the one that actually energizes the relay for 2 seconds. Maybe checking the wire to see if it's messed up will explain why your pump does not energize at all?

 

I have a gray wire, a purple wire and a black wire coming out of the fuel tank. I hooked a wire to a battery (pos+) and put it to the gray wire, pump did not come on. So then I put another wire on the neg battery post and put it to the black wire with the positive hooked to the gray wire and the pump still did not come on. I will check the wires up by the relay as you guys stated when I have someone here to help me, I just thought that with the way I put power directly to it that it should have come on. This was done with the harness that comes out of the tank disconnected from the bottom of the car. Is this the way to check it? If it should have come on, maybe I will drop the tank again and double check the connections inside the tank. Man,this is killing me!

 

The pump should have run during your test with the battery. Is there 1 black wire or 2? If there is 2, did you try both?

If I were you, I'd check for voltage at the rear connector first just to be sure you have power. You can use a volt meter but the best test is to rig up a spare taillight to the Gray and Black wires coming from the front. If the bulb lights BRIGHT, you have good Voltage and Amperage.

If you have good power, I'd suspect a bad sending unit. Hook up an Ohmmeter from the Gray wire to the Black wire. If you get an "OL" reading then your problem is in the tank.

 

After verifying that I had power to the back of the car , I figured it had to be the sending unit. So, I dropped the tank again, tested some wires and the pump itself and found that it was a bad connection where the wires plug in to the sending unit from the pump (the round part where all the lines go through that sits on the O-ring) The prong sticking down that is for the gray wire was filthy and so was the connector that goes to it. I cleaned them up and now it works great. I still can't believe it was something that simple, but I am glad it was! I can't wait to take this thing to the track, it seemed to have much more power today than when I first got it going before the other pump died.
Thanks everyone for helping out!

 

Glad you found it, it's always something stupid and simple. Too bad you had to drop the tank again though.