AT4 T/A

I'm trying to put back together my '89 IROC L98. I just got a new transmission, new fuel pump, and new injectors. Today I fired it up, simply to take it to the car wash a 1/2 mile down the street and wash the dirt off. It's been a couple of years since I've been able to drive her, so yeah, I kinda got on it. Tires spin, I smile, then the SES light comes on and I lose power. Car stumbles for a second then dies. It won't start again. I pull the trusty paperclip out of the center console and stick it in the ALDL. Code 22 is says. I remember that's TPS, but it looks like it could be a fuel cut off relay or MAT temperature. I'll break out the multimeter on it tomorrow and reset the TPS. What concerns me is the engine won't start at ALL. Since the fuel cutoff relay is potentially involved, do you guys think there's a chance my brand new Walbro pump gave up the ghost?

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Kevin91Z

Turn the key and listen to the gas tank. You'll hear the fuel pump run for two seconds. If you dont hear anything, then its either the pump, or its wiring.

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birdtojag

According to the diagram, the fuel pump priming circuit runs with a relay and shuts off after about 2-3 seconds. The oil pressure switch could be bad too. The oil pressure switch senses that there is oil pressure and completes the circuit to run the fuel pump (built in engine safety). This might be your issue too. Good luck with the issue.

Vader

Look more closely at the schematic. I think you'll discover that the oil pressure switch is in parallel with the fuel pump relay, not in series. That means the fuel pump will get power from either the oil pressure switch OR the relay. Either one can fail and still allow the fuel pump to run. There is no fuel pump safety switch based upon engine oil pressure.

AT4 T/A

The fuel pump is working correctly. I released pressure to the fuel rails through the schrader valve, and upon turning the key I heard the pump run and repressurize the rails.

I replaced the TPS just a few minutes ago. I've misplaced my multimeter, so I had to eyeball it based on where the old sensor was.

The car still refuses to start. I reset the computer, and it's not throwing a code 22 any longer.

Any ideas guys? I appreciate your help!

AT4 T/A

I'll post this in the hopes that it will help someone else that encounters the same problem:

Despite the fact that the computer threw a code 22, the TPS wasn't the issue. I replaced the TPS and it still wouldn't start. It turns out, the ignition module had gone bad. Once I replaced it, the engine fired up immediately!

I had tried some starting spray through the MAF, then I checked fuel pressure at the rail. The fuel pump would run and the rails would pressurize. I pulled one of the spark plug wires off the plug and looked for an arc while cranking. NOTHING. Put in a new module and it worked great!