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1990 Turbo Grand Prix - turns over but wont start - Fuel pump doesnt turn on?


jongrappin

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The car was running badly then stopped starting. The car turns over however the fuel pump will not turn on unless i use the fuel pump test connector....

 

Is it the fuel pump oil presure switch? or my oil pump puked? it started to overheat the last time it started and it was just idling?

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I have swapped the fuel pump relay with another one that is good.

The fuel pump was new about 3 months.

 

Next steps:

I will try is to bypass the oil pressure sensor switch if this works, i will replace it.

I will test the wire going from the ECM to the relay, also I will check the ground to the relay.

 

Have you checked your fuel pump relay?
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About the Oil Pressure Sensor... Does this commonly go bad? would this cause the car to not start? How do I determine if the sensor is at fault or if it is a bad wire or possibly a bad oil pump???

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I had a egr tube crack one time, actually several of them.. shot a blade of hot gasses under the plenum where I could not see and burned the injector wiring and made it not start. I replaced the egr tube and didn't notice problems untill later on. it appeared perfectly normal until I pulled off the upper plenum.

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More info.... after digging deeper into the fuel pump relay, wiring, oil pressure sensor, etc... I found the orange wire(480) going into the relay providing 12.2 volts thus this should mean the oil pressure sensor switch is working, The Green/white wire(D7) from the ECM called "12 Volt pump relay drive" has no volts.

After doing this i noticed that my dash lights are not turning on properly! The Service Engine Soon Light does not come on, nor does the low coolant light. These lights should turn on when the key is forward as they do in my other TGP and as they did prior in this car as well. The check gauges light is on when key forward, as it always has been..

Other thoughts... When I was swapping out the ECM one of the times I may have forgot to disconnect the battery cable!, if i did this would it fry a relay or a fusible link?? I have tested both ECMs on the other car and both run flawlessly. I have checked all fuses and tried swapping some of the relays to test them, which ones should i test? Also where should i test fusable links?

 

Where do I start to diagnose the problem with the Service engine soon light not coming on when key turn forward.

 

...This is starting to piss me off, I think I may just pull the front clip off this one and but it on the 2nd TGP as thats all it needs!:think:

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Would this explain why the fuel pump isnt turning on or the the service engine soon light isnt on when key is in run position?

I had a egr tube crack one time, actually several of them.. shot a blade of hot gasses under the plenum where I could not see and burned the injector wiring and made it not start. I replaced the egr tube and didn't notice problems untill later on. it appeared perfectly normal until I pulled off the upper plenum.
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Are your bulbs on the dash good? I would suspect a burned out bulb first.

 

The ECM being bad could explain a lot. I had the ECM in my '96 Cutlass killing brand new alternators before I figured out that was what was happening.

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