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Jeep Grand Cherokee fuel pump not working


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camofranklin18
New User

Feb 13, 2017, 2:15 PM

Post #1 of 5 (318 views)
Jeep Grand Cherokee fuel pump not working Sign In

Hey guys! I've been having troubles with my 1994 jeep Grand Cherokee's fuel pump ever since i removed the battery and put it back in. Originally i thought i blew a fuse or a relay but they're both fine. I dropped the tank and took the fuel pump out to plug it in externally so i could look at it closer, i found it running intermittently so thought it was a bad pump and replaced it. It started working straight away for 6 or so starts but now its just not working again. I'm thinking it has to be something electrical because the problem only happened after i removed the battery and put it back in! all connections look sound and as said before fuse and relay are good. Any other ideas? HELP!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 13, 2017, 2:37 PM

Post #2 of 5 (304 views)
Re: Jeep Grand Cherokee fuel pump not working Sign In

There isn't a magic answer for this. The circuit will have to be troubleshooted by following a wiring diagram.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
Veteran
kev2 profile image

Feb 13, 2017, 3:14 PM

Post #3 of 5 (295 views)
Re: Jeep Grand Cherokee fuel pump not working Sign In

can you use a wiring diagram test light and a DVOM?
If so we can make suggestions -


camofranklin18
New User

Mar 2, 2017, 10:12 PM

Post #4 of 5 (245 views)
Re: Jeep Grand Cherokee fuel pump not working Sign In

Hey guys, so i have a long and painful update.

I took my car to a mechanic as i'm not too savvy with electrics. The mechanic told me the fuel pump was bad, although i had just replaced the fuel pump two days earlier. They assured me they circuit tested everything and nothings wrong, just the fuel pump so i got a 'bad part. After lots of doubt i left it to the pro's and gave them the go ahead, i got a new fuel pump under warranty which was fortunate. $750 later they give me my car back which i drive home and park. Two hours later i try to start it and nothing. I call them fuming and they come and tow it back to their shop.

Mechanic calls me a week later and says ever since he got it, it hasn't stopped starting. He cleaned up all electrical connections, changed the negative battery terminal and its good to go. I drive it home and park and a few hours later, YEP! nothing.

I thought it might now be the security system as i'm now frustrated and thinking of every possibility so i lock all doors and just open the drivers side with the key which shuts off the security, and it started! i thought i had finally figured it out that its an old car and the security a bit dodgy and i just need to disconnect the security module!

I drove it to work, stopped it and then it wouldn't start again, when i tried the same trick with the door it still wouldn't start.
I've bypassed the fuel relay and the pumps whining but there isn't any pressure coming out.

Any suggestions? ANY? if it was the security module it would shut off power to the pump all together would it not?

This is the third pump, i refuse to believe its a 'bad part'.

I just permanently grounded the security module and it didn't start straight away, although the next time i bypassed the fuel relay it started twice, then again when i put the relay back in.
It's like its got a mind of its own and i'm completely lost


kev2
Veteran
kev2 profile image

Mar 3, 2017, 7:36 AM

Post #5 of 5 (224 views)
Re: Jeep Grand Cherokee fuel pump not working Sign In

STOP unplugging things randomly this will throw codes force changes that will 'confuse' system, Thinking a theft issue, setting defaults etc.
first suggestion start by scanning for codes, Even if CEL is off - a limited OBD system but to easy to ignore. Post all codes.
Will the security light come on at start?
Is there a remote starter?


What is above answers?


NEXT - most likely place to start-
>>" bypassed fuel relay and the pumps whining but there isn't any pressure coming out." this is where to start. NOT unplugging systems.
KOEO relay jumped - Confirm there is 12v at pump, ground is good and the whining is actually fuel pump -






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