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Low voltage to fuel pump?

Old 06-26-2018, 02:31 PM
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Default Low voltage to fuel pump?

Trying to diagnose a "crank, no start" condition and went to test the voltage to the fuel pump. I disconnected the wiring harness, and used a voltmeter with the negative lead connected directly to the battery (via jumper cable out the window) and went about checking the voltage to each terminal. It read 7.5V when I pushed the probe into the top (row of three), center hole. It read this value no matter whether I was cranking, or just had the key to ON (which I suspect is because of how I grounded the probe). When I disconnected from jumper cable and tested voltage across the terminal, I got 6.5 volts. I also tested the battery, which read above 16V.

Is this too low? Should I read battery voltage at the wiring harness? I've checked all the fuses and relays, which are operating properly. Thanks so much for your help.
Old 06-26-2018, 04:13 PM
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The fuel pump will be powered only when the engine is cranking over or running. If there is voltage when doing neither, its not the fuel pump wire.
Old 06-26-2018, 06:47 PM
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Got ya. The more I thought about it, the more that made sense. I guess that wire was for the fuel level? I can't find a diagram that explains what each of the five wires in the fuel pump harness connect to, so I don't know what specifically to test. Everything I read just says, "check for voltage at the fuel pump", and assumes that I know which parts to probe. Do you happen to know which of the five wires in the harness I should test for the fuel pump wire and for ground?

Also, I've seen you comment in other posts that the pump would only be powered when the engine is cranking or running, but the Haynes manual says that the fuel pump will be turned on for two seconds after turning the key to the ON position to charge the fuel system. And that you should be able to hear a light whirring while it does that. Am I misunderstanding something? Anywho, I really appreciate you taking the time to help me diagnose the problem.
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