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roadrash88 08-07-2013 06:53 PM

2004 jeep grand cherokee
Having problems with fuel pump. After about 10 minutes idling the fuel pump starts kicking on and off. I have changed the fuel pump, fuel filter, fuel tank, spark plugs, blown air through the fuel lines and is still acting up. Please any suggestions.

Frango100 08-07-2013 08:35 PM

Re: 2004 jeep grand cherokee
Fuel pump relay?

roadrash88 08-07-2013 08:36 PM

I tried swapping relays out didn't make a difference but I'm gonna buy a new one tomorrow

Frango100 08-07-2013 08:45 PM

Re: 2004 jeep grand cherokee
If you already swapped it with an other known good relay then its no use to buy an other one.
Did you measure the voltage to the fuel pump and did it go to 0 V?
The fuel pump relay is switched by the PCM. You could check the fuel pump wiring by disconnecting connector C3 from the PCM and connect pin 19 from the wire bundle connector to ground. The fuel pump should run continuosly. If it still goes on/off, then there is some electrical problem in wiring. If it doesn't, most probably the PCM is the culprit. I'm not sure for how long you could let the pump run like this without fuel usage by the engine, but i would imagine that the fuel pressure regulator will return the fuel to the tank.

roadrash88 08-07-2013 08:47 PM

Where is the PCM located

Frango100 08-07-2013 08:53 PM

Re: 2004 jeep grand cherokee
Under the hood, against the bulkhead close to the right fender. Its just behind the coolant overflow reservoir. It has 3 connectors with a lot of wires to it.

roadrash88 08-08-2013 06:16 PM

I can't figure how to check by grounding pin 19. But while idling when it starts kicking on and off it stays on for 3 seconds shuts off for 15 and just keeps repeating.

roadrash88 08-08-2013 06:24 PM

And while driving the sentry key indicator light came on but went off after I killed and cranked it

Frango100 08-08-2013 08:04 PM

Re: 2004 jeep grand cherokee
1 Attachment(s)
With ignition switch in run and grounding pin 19 from connector C3 from the PCM will activate the fuel pump relay and this will send power to the fuel pump. If the pump runs ok like this, the problem is most probably in the PCM.
How did you determine that the fuel pump is on for 3 seconds and off for 15, did you measure the voltage?
When you switch the ignition in on but donīt start, the PCM will switch on the fuel pump for 3 seconds and then switch off if it doesnīt get a speed signal from the engine.
Did you already check for any fault codes set by the PCM? Ignition switch off/on three times and leave in on at the third time. The odometer will show DONE or any fault code(s).

roadrash88 08-08-2013 08:13 PM

I could feel the pump running through the fuel lines at the fuel filter an I timed it

roadrash88 08-08-2013 08:14 PM

And it's not throwing any fault codes or at least not kicking on the check engine light

Frango100 08-09-2013 01:44 AM

Re: 2004 jeep grand cherokee
You can have a code set without the check engine light on, so if you didnīt do the keydance yet, give it a try.
Did you feel the pump running with the engine off? I donīt believe that the engine will stay running when the fuel pump is off for 15 secs.

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