Fuel and Ignition Fuel Pumps and Systems, Ignition and Spark Systems

Fuel pump dead/dying?

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Old 09-24-2013, 02:29 PM
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Fuel pump dead/dying?

Got out of class yesterday morning and car wouldn't start. Check the Schrader valve and there was little to no pressure. got it towed home, changed fuel filter and it started but died after a few seconds. Went and bought a pressure tester and prime using the fuel pump prime connector and it primed to 40 psi and held. Started the engine and the pressure just dropped until the engine died. Is this a good sign of a bad pump or could the regulator be an issue? Car is the 95 Z28 in sig.
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Old 09-24-2013, 02:53 PM
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Re: Fuel pump dead/dying?

Odd thing is, once it runs/dies, I can't get it to prime again without letting it is for several minutes.
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Old 09-24-2013, 07:10 PM
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Re: Fuel pump dead/dying?

Update: After letting the car sit for about 45 minutes, I turned the key to "ON" and got good prime to the fuel pressure gauge. Car started and ran fine for several minutes. Shut it down and started again 2 more times, however, each time after the initial start, the pressure dropped while running and was about to stall before the pressure jumped back to normal and stayed running. Tried a third time and the pressure slowly dropped during idle until the engine stalled, then would not prime again. Now I'm not sure if is indeed the pump going bad or a bad connection somewhere.
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Old 09-25-2013, 07:17 PM
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Re: Fuel pump dead/dying?

Seems this site doesn't get the traffic it used to. Hopefully I can figure this out rather quickly.
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Old 09-27-2013, 11:18 AM
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Re: Fuel pump dead/dying?

The pump can "heat soak".

Check the voltage at the harness connector above the rear axle. If there is a defective wire or connection in the circuit, it would show up as reduced voltage.

http://shbox.com/1/fuel_pump_wiring.jpg

http://shbox.com/1/fuel_pump_connector.jpg

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Old 09-27-2013, 10:48 PM
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Re: Fuel pump dead/dying?

Using the fuel pump prime connector, I get 12.1 volts to the fuel pump connector. Priming the pump via the prime connector, I can get it started once maybe twice and then it will no longer prime, even using the prime connector under the hood. I have a new pump going in tomorrow and will post back with results.

Edit: Should there be power to the connector with just the key in the "ON" (not using the prime connector) position or would there only be power while running?
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Old 09-30-2013, 10:01 PM
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Re: Fuel pump dead/dying?

Was indeed the fuel pump.
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