88 xj fuel pump issues. help! - JeepForum.com
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post #1 of 5 Old 12-20-2016, 02:51 AM Thread Starter
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88 xj fuel pump issues. help!

hey guys, im new to the fourms but hopfully someone can shed some light on my issue.

I own an 1988 jeep xj, 4 door. 5 speed, 4x4. lifeted about 6.5" on 35s. have only had it about 2 months. ran great until i decided to repair the floor pans due to rust. so i got rid of all the carpet, took all the interior out, dropped the gas tank to patch some holes in the trunk area. got all the floor pans replaced, bedlinered the inside, and installed all the interior back, it looks great. i wire brushed the outside of the fuel tank, and painted it black. i undercoated the jeep aswell. well i went to reinstall the fuel tank and everything and it wont crank

i dont exactly hear the fuel pump runnning like i do on my comanche.
i checked the wiring harness for power with a test light, and no power going to the harness, checked it under the back seat.
checked the relay under the hood on the passenger fender and changed it.
checked all fuses under the dash for bad ones, all are good.
i need to check for power going to the ballist resistor in the driver side fender i guess, should have 12v going in, and 6v coming out right?
i know my comanche has a ground in the drivers tailight for the fuel pump to work, does the cherokee have a ground for the pump anywhere? ive been told its grounded to the tank itself.
MY FUEL GAUGE DID WORK HOWEVER! dooes this mean i am getting power to the pump? and possibly the pump itself is bad?
another thing is i didnt tighten the straps yet on the tank, so its hanging and not snug to the floor of the jeep, and i undercoated the jeep so i was wondering if the fuel pump is grounded by the tank, does the tank gotta be grounded by the floor of the jeep when its pulled tightly together by the tank straps. and if so will the fact i painted my tank and undercoated my jeep cause it to not ground properly?

im stuck guys, i need some ideas, and what to check and all with a multimeter. or possibly run a new relay and new wires to get this pump working again. im so close to getting her road worthly again! everything worked good before i started fixing her up

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post #2 of 5 Old 12-20-2016, 02:54 AM Thread Starter
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i need to check my fuel pump wiring harness with a multimeter too, i dont know if my test light had proper ground!
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post #3 of 5 Old 12-20-2016, 03:21 AM
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Try banging on the tank with your hand before starting or have someone else bang it as your trying to start it. If if goes on your pump is bad. Can't hurt to try before you start taking everything back apart.

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post #4 of 5 Old 12-20-2016, 05:53 AM
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Ground is inside the let quarter area behind the spare tire.

Ballast resistor is battery voltage in and about 8 volts out. It can be bypassed.

Here's a way to deal with the ground:


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post #5 of 5 Old 12-20-2016, 09:26 AM Thread Starter
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thanks guys, yeah that ground behind the spare tire, i made sure it was a clean surface and grounded well when i bought it, cause when i got it all the interior was out and the tail lights didnt work.
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