Remember the Geo? Fuel pump won't prime when switched to the "ON" position, therefore the car will not start. No pressure in the fuel lines either. Signal from starter to ECU is good on the fuel pump relay and there is power to powerwire (red and black wire) an the relay as well. Ground seems good.

Ok, so I checked all the wiring on the Geo for the fuel pump and fuel relay. All seems fine. Pump definately works, relay seems good but there is no power from the ECU to the relay. (Therefore no power to trip relay and send power to fuel pump) According to GM manual there should be power from the ECU when the ignition is turned "ON". Rumor has it the engine light will be off when the key is in the "ON" poition if the ECU is bad. Light is on in this case. PNP seems to be working fine. Think my ECU is dead?

 

well..bad pcm's are rare..but it happens..

can you get scan data?...a couple things COULD inhibit the pcm from turning fuel on...like theft codes..also,a wide open tps sensor reading will turn fuel off..try and start your truck with your foot alll the way to the floor on the gas pedal and you'll see what I mean.

 

Well I can get the codes maunally and look them up on the web. Or do you think I should just bite the bullet and get a scanner?

 

not for a jizm,i would not..its too diffrent than regular gm..i might would check the tps with a voltmeter..it should have a varying 5 volt rference...about 1 volt closed,to about 4.9v wid open throttle

 

I'll get on that tomorrow. Thanks

 

Ok, When testing the TPS with a multimeter I get:

Red: Power
Black: Ground

WOT Closed
Yellow: 5.04V 5.04V
Green: 3.84V 0.64V

Am I ok? If its not the TPS, anything else to check before I search for a ECU?

Thanks Argon

 

looks good..but make sure that green moves with the throttle...up close to 5v wide open..then,its probably ecu time i'd guess

 

Yeah it fluctuates with the movement of the throttle. Someone told me to recheck wiring between the ECU and relay, then the relay and pump with an OHM meter. After that I need to disconnect the battery, unplug the ECU, plug it back in, reconnect the battery and try it again. Sound legit?

 

Ok Argon I need your help again. I replaced the ECU now (got it cheap off of craigslist). The car still will not run. I doubt that both ECUs are bad so I don't know what else it could be. I have a theroy, sort of. I put some more gas in the tank and after trying to start it, I noticed that despite my repairs to the fuel spout and fuel lines that there was still a leak from the filler tube to the tank. Would a loss of pressure in the tank prevent the car from starting?

Note: The pump will not prime again. I made a jumper for the pump relay and it would prime when the ignition turned to "ON" position. When I cranked the engine however the pump would stop.

If not the pressure cause the pump not to run, maybe a ground for the starter signal?

Thanks again!