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What color to wire powers fuel pump?
Thread Starter
Seasoned Member
Joined: Jan 2010
Posts: 251
Likes: 0
From: JERSEY ALL DAY
Year: 1989
Model: Cherokee
Engine: 4.0L
96 xj low voltage problem at fuel pump. I want to run a 12v power supply back there so i can get fuel pump to run.
What color wire powers the fuel pump out back?
What color is ground? I had a mice problem and feel thats the culprit.
Runs on starting fluid
What color wire powers the fuel pump out back?
What color is ground? I had a mice problem and feel thats the culprit.
Runs on starting fluid
Thread Starter
Seasoned Member
Joined: Jan 2010
Posts: 251
Likes: 0
From: JERSEY ALL DAY
Year: 1989
Model: Cherokee
Engine: 4.0L
BUMP!
12V cranking at fuel pump
5V steady with key on
fuel pump does nothing
must be ground issue.
I need a pinout of wires, or wire colors, or some sort of schematic. so i know where ground wires are where 12V hot should be.
comeon guys!
fuel pump worked perfectly 2 months ago. I had a rat problem in that 2 month period a few wires got chewed under my seat. they got in from when i did mu clutch. and the shifter was out. i fixed the broken wires i saw. but any help is appreciated
12V cranking at fuel pump
5V steady with key on
fuel pump does nothing
must be ground issue.
I need a pinout of wires, or wire colors, or some sort of schematic. so i know where ground wires are where 12V hot should be.
comeon guys!

fuel pump worked perfectly 2 months ago. I had a rat problem in that 2 month period a few wires got chewed under my seat. they got in from when i did mu clutch. and the shifter was out. i fixed the broken wires i saw. but any help is appreciated
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
I'll subscribe and tell you when I get out there. I know orange is constant power from the resistor which is the 5v your getting. One wire can't remember the color is 12v prime and the other is the sender. Pretty sure the pump is grounded to the tank
Thread Starter
Seasoned Member
Joined: Jan 2010
Posts: 251
Likes: 0
From: JERSEY ALL DAY
Year: 1989
Model: Cherokee
Engine: 4.0L
thanks let me know im lost here.
Seasoned Member
Joined: Sep 2009
Posts: 454
Likes: 0
From: East Texas
Year: 1997
Model: Grand Cherokee
Engine: 4.0
Looking at a diagram for 4.0 engine there are 5 wires going to the fuel pump module.
1. Relay output to fuel pump module Dk Grn/Red (This is the power)
2. Sensor Ground PCM to module Blk/Lt Blu
3. Fuel Level to Instrument Cluster Dk Blu
4. Low Fuel to PCM low fuel sense Dk Blu/Wht
5. Ground Blk
1. Relay output to fuel pump module Dk Grn/Red (This is the power)
2. Sensor Ground PCM to module Blk/Lt Blu
3. Fuel Level to Instrument Cluster Dk Blu
4. Low Fuel to PCM low fuel sense Dk Blu/Wht
5. Ground Blk
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It seems you are thinking a chewed wire is the issue, but any time you have a fuel pump issue, first check the relay. Mine went bad, and I at first checked everything but that. Swap the fuel relay with the fan relay. See if you get a different response. Worth a shot.
Looking at a diagram for 4.0 engine there are 5 wires going to the fuel pump module.
1. Relay output to fuel pump module Dk Grn/Red (This is the power)
2. Sensor Ground PCM to module Blk/Lt Blu
3. Fuel Level to Instrument Cluster Dk Blu
4. Low Fuel to PCM low fuel sense Dk Blu/Wht
5. Ground Blk
1. Relay output to fuel pump module Dk Grn/Red (This is the power)
2. Sensor Ground PCM to module Blk/Lt Blu
3. Fuel Level to Instrument Cluster Dk Blu
4. Low Fuel to PCM low fuel sense Dk Blu/Wht
5. Ground Blk
If there is another easier route to tap the wire inside Jeep. I am all ears
CF Veteran
Joined: Sep 2011
Posts: 4,172
Likes: 4
From: Riviera, Texas
Year: 1998 Sport
Model: Cherokee
Engine: 4.0
I was going to leave a post until I noticed the original date 12-04-2011
Thread Starter
Seasoned Member
Joined: Jan 2010
Posts: 251
Likes: 0
From: JERSEY ALL DAY
Year: 1989
Model: Cherokee
Engine: 4.0L
I fixed it and scrapped the rig, floors were gone nothing was good on it.
The problem was the ground wire from harness going to the ground pin on outside of sending unit was just bad from corrosion. I cleaned a new spot and soldered a new ground right to it and havent had a problem since. Thanks though guys.
Been online since 94 or so. I noticed you have those who **** OP didn't search before post. Then those who think the world came to end if you post on an old post. Someone is always going to complain. lol. Can't win.
Did you know the answer?
Seasoned Member
Joined: Sep 2009
Posts: 454
Likes: 0
From: East Texas
Year: 1997
Model: Grand Cherokee
Engine: 4.0
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by CrawlerYJ
I did.
Been online since 94 or so. I noticed you have those who **** OP didn't search before post. Then those who think the world came to end if you post on an old post. Someone is always going to complain. lol. Can't win.
Did you know the answer?
OK, it's 2017, but there are STILL some of us who have older (ancient) Jeeps.
I just recently took my 1994 GC Limited out of storage and am trying to get everything
healthy again. So yes, while it was a hot topic back in the 1990s, there are those of us
who are still actively looking for how to diagnose and fix fuel tank senders.
So for those who answer old posts-- even years later-- THANK YOU.
I just recently took my 1994 GC Limited out of storage and am trying to get everything
healthy again. So yes, while it was a hot topic back in the 1990s, there are those of us
who are still actively looking for how to diagnose and fix fuel tank senders.
So for those who answer old posts-- even years later-- THANK YOU.




