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Low voltage at fuel pump

10899 Views 5 Replies 3 Participants Last post by  HUASKER POWER
I have a 93 K 3500 7.4 and I only have 2.7 volts at the fuel pump. I can hook up a 12 volt jumper wire to the fuel pump and the truck runs fine. I have power to the relays fuses and all fuses are good any Ideas ?
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I'm not familiar with the '93 wiring. Usually with this kind of problem, I get a wiring diagram and a voltmeter, start at the battery, and work my way down the circuit. Where the voltage is 12 V, the circuit is good. The problem will be between the last point where you had 12 V and the point where the voltage is 2.7 V.
X2 on Shortys reply & I would check at the fuel pump relay first. Check the wire connectors for being clean & tight, & check for proper voltage in & out. After your engine is running the power for the fuel pump is routed through the oil pressure switch so check it too.
Thanks guys, the fuel pump was bad but I also put a new FP Relay in from NAPA that was defective after I just happened to try the old Relay it started right up.
Glad you got it fixed. Since diagnosis can be most of the battle, can you share with us how you determined that the fuel pump was bad?
I pulled the fuel pump out and hooked two wires to the + - and it would not run.
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