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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 21599
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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Here, I am having a problem getting electrics to the fuel

Customer Question

Hi, Chris, Don here, I am having a problem getting electrics to the fuel pump on my 1990 Jeep Cherokee. I have replaced ECU, all the relays test good, if I hotwire pump, it works fine but just not getting electrics under normal circumstances.
JA: How many miles are on the car? Has the car been starting normally?
Customer: 149,000+ and it won't start, fuel pump isn't running when I turn on ignition and/or crank starter.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes. I have replaced ECU (foolishly probably) and checked all relays, they check good. I've checked wiring from fuel pump relay to pump, it's good.
JA: Anything else you think the mechanic should know?
Customer: Not that I can think of.
Submitted: 4 months ago.
Category: Jeep
Expert:  sprinkles08 replied 4 months ago.

Hello and welcome to JustAnswer!

There are quite a few things that you could have going on. It's definitely possible that the PCM could be down either due to internal failure or a loss of power or ground to it. If lack of fuel pump operation is the only issue then you could have a relay or wiring issue. There is also a resistor in the circuit to drop voltage to the pump while running, but if the resistor had failed then the pump should still run initially when the key is turned on.

Does the engine start and stay running when you apply power to the pump?

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