screamingpete87

i have a 87 5.0tpi iroc when i plug my fuel tank in my car will not start not even a single fire when i unplug my tank the wires to the sending unit the plug under the car in front of the tank my will run at idle but obviously starves for fuel when i get the gas. Why would plugging my fuel pump in stop the car from running? Thanks for your help i need my baby running before snow flies and the weather is still good!!!!!!!!!

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gmpptech

The only thing I can think of is that you have other things fed off the circuit that powers your fuel pump and that circuit has high resistance before them. (such as a green/corroded wire) Check the voltage at your pump connector with the engine cranking, should be close to battery voltage. Then plug it in and recheck voltage on those wires while cranking. If it goes lower than your first reading by more than a volt you have a bad connection in the circuit. This means the voltage will go to low for other things to work on that circuit when the pump(high load) is plugged in. On a lot of third gens the pcm and other sensors branch off that same circuit. This is why it fires for a bit only when the pump is unplugged.