I know its not a Chevy Truck, but technically its GM and I really need some help / advice on this. I recently towed home a 97 Geo Prizm, which is essentially a GM bought and sold Toyota Corolla.


Got the Prizm. Details are the following:

There are 248,600 some odd miles on the car. It ran perfect and relatively trouble free before it sat. No major burning of oil, no major leaks, no raps and taps or knocking from engine. Was leaking fuel from spout and needed a blower motor in the dead of winter so we got my girlfriend a different car figuring it might be more involved then what meets the eye. The car then sat for a year in her parent’s driveway and was only started a few times soon after it sat. Then it was never started at all.

Problems:

When got to mess with it, the car would crank but not start. No fuel pump “noise”. Needed fuel spout replaced and breather tube replaced on gas tank. The car needs two struts for inspection. Needs brakes cleaned up.

Recent Issue:

Replaced the spout, the breather and the fuel pump. Turn the ignition to the “On” position and no noise from the fuel pump. Pulled it out and tested the new pump directly, it worked fine. Tested the leads on the wire harness, nothing. SO I purchased a relay off the Internet (for cheap thank God) and replaced that as well. No noise from the fuel pump at all when the ignition was placed in the “On” position. Tested the wire harness on the relay. I used a wire schematic from the GM Shop Manual and found that there are two signals (or so its seems, not 100% on reading wire schematics) from the car that need to reach the relay; The starter and the ECU. Well the ECU signal is there for sure as I tested it with a test light. The starter signal is there too. I accidentally jumped the starter with a power lead on the relay and the starter cranked for a split second, so it verified the particular lead I was looking at was for the starter. Now here is where I am confused:

1. Does the starter need to be cranking before the fuel pump is engaged? If so I have never heard of this, I mean no prime until cranking. Maybe it’s a Toyota feature?
2. Am I possibly looking at the wrong relay? I can’t find the location of the starter relay, but the relay I am screwing with is definitely in the location the manual points out as the fuel pump relay location (or as the book calls it the “a circuit open relay”).
3. If I am wrong about the first two, now what should I look for? I was thinking I should top the oil off, hook the alternator back up, put the valve cover back on and try firing it up. Someone told me a fuel pump might not kick on without oil pressure. I just need it to prime, so I didn’t try this yet.

ANY HELP WOULD BE GREATLY APPRICIATED! THANKS!

 

bump

 

Circuit open is most likely the starter, it's always "open" until you close it and engage the starter. Keep looking for that relay because if you can get the starter to chirp with no fuel delivery or pump noise its not pumping fuel. Also check out the fuel pressure regulator by pulling the hose out and cranking real quick. If youve got fuel then its pumping obviouslybut you shouldent see any. But im pretty sure what your looking at is the starter relay.

 

ok..looking at the schematic,(the pic works if you click on it)..

as any chevy,you have 4 fuel relay holes...12v,ground,out to pump,and a command..what a relay does is link the 12v to the out wire when told to..but you know that already..what you need to do is get yopur test lite on that blu/blk wire,and turn the key to crank...if its hot,then go check it at the pump...if not,then back up the other way towards the fuses..

still no good?..hook your test lite to power and check for the ground,and then get in the command hole from the ecm,and see if the ecm grounds it when key turned oto crank.




here is the circuit description......



When the ignition switch is turned to the "START" position, the circuit opening relay will be energized to allow the fuel pump to operate and pressurize the system. The fuel pump will continue to operate if the Engine Control Module (ECM) receives an ignition signal when the engine is started. The fuel pump operates as long as the circuit opening relay is energized by the ECM. When the circuit opening relay is de-energized, the fuel pump will stop operating. The fuel pump delivers fuel to the fuel rail where the pressure is maintained by the fuel pressure regulator at 284kPa (41psi) higher than the pressure inside the intake manifold. Excess fuel is returned to the fuel tank through a return pipe and hoses.


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Ok. Thanks Argon and ChevyCowboy. I will test it again tomorrow afternoon and see what has power and what doesn't.

Yesterday I had power from the ECU when turning ignition to the "ON" position. Made me a little relieved because I was worried the ECU might have sh*t itself. I need to test the starter signal again. Like I said before, pump definately works on its own, but I did not get any power at the plug.

Just out of sh*ts and giggles, It wouldn't have anything to do with oil pressure would it?

One more thing, now looking at this car before I even touched the engine. Battery was half dead and there was plenty of (stabilizer treated) gas in the tank. I kicked it over and it cranked slow, real slow, and the pump did not fire up. I just found out yesterday that the alternator was seized.

Could the slow cranking plevent a signal from the starter not allowing the pump to run?
Is there anything that would prevent priming like a bad regulator?

Thanks guys!

 

LOOK AGAIN AT THE CIRCUIT DESCRIPTION...WHEN YOU TURN THE KEY TO START,IT will BE ENERGIZED IT SAYS..so i'd go there...pull the relay out and see what you have where

 

Ok, then I did that once already. Put a test light to the relay socket and got power (signal) from the ECU and the starter according to the socket diagram in the back of the manual. You got the three prongs across the top of the harness, and two on the bottom separated by a space. One side should be starter and the other ECU, right? The ECU one had power. When I went to test the other side (starter), the starter jumped. So now I should put the relay in, turn the ignition to "ON" but not start it, and see if there is power to the wires that run to the pump right?

Also, I bought a "open circuit relay" specifically for the geo, but the last two or three digits are different from the one in the car. Look the same, same setup, shape and plugs but the new one is black. Old one is green. Should I return it?