'96 xj new fuel pump; wont start now - JeepForum.com
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post #1 of 8 Old 02-22-2020, 07:40 PM Thread Starter
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Xj '96 xj new fuel pump; wont start now

So recently got my jeep back into commission after having to replace a rear bent axle (local mechanic took care of it). The next thing on the list was replacing the fuel pump. Had been having to prime it almost every time I took it out. Long story short, bought a Bosch pump, strainer, and new rubber gaskets.
Me and a friend replaced the old pump on my 1996 4.0l 6.0 xj classic without dropping the tank cuz its on the side of the tank. Well, thought I had hit it off lucky but when we were replacing it, I noticed the wired looked all jacked up. (see photo)
[IMG][/IMG]
There was a red wire soldered into the sending unit's connector. Traced the Red back to the engine bay where I lost it. The whole thing was still plugged normally into standard place. I cut the Red to remove the sending unit *and replace the pump/strainer* and and I think that was a mistake cuz after putting everything back together the way I found it everything worked fine... till my friend heard a clicking from under the hood.
The jeep started good and strong several times and the clicking stopped. He could hear the pump working and the 'low fuel' light was lit. However, when I took it down the neighbourhood street it sputtered and then went totally dead.

It cranks but the pump isnt powering up anymore with 'key on' and the 'low fuel' light isnt popping on anymore. Switched a couple relays and that didnt change anything. Any thoughts? Any thoughts why that Red wire was put in in the first part?

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post #2 of 8 Old 02-27-2020, 09:39 PM Thread Starter
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So update, traced that red wire up under the hood where it was wedged deeply into this harness...



It wasnt connected to anything and slipped out from beside the harness with very minimal effort. Still perplexed why anyone would do this. Went to the junkyard and found a new connector from another 96. Unfortunately the sending unit had already been picked. Planning on cutting the wires below where the new red wire was soldered into the line and putting the new connector on.

Relays tested good and connector Jeep side is receiving voltage.
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post #3 of 8 Old 02-28-2020, 07:15 AM
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"Me and a friend replaced the old pump on my 1996 4.0l 6.0 xj "

this is a 1996 jeep Cherokee XJ with a 4.0L engine what is 6.0?

Fuel pump is IN tank and requires tank removal. What do you have?
Sounds like an external pump with rigged wiring.
Add a picture of the pump on side of tank.

also tell us the colour of the wires at fuel pump connector.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 8 Old 02-29-2020, 03:40 PM Thread Starter
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"what is 6.0?" that is V6 engine.
The fuel pump and sending unit are located inside the tank but are accessible without dropping the tank (because it is located on the side of the tank). Its an electric sending unit and pump and everything sits in the tank.


The wires coming from the connector are purple/white stripe; red/black stripe; and solid yellow, orange, and black
After unravelling the electrical tape heres the unit's connector wiring...
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post #5 of 8 Old 02-29-2020, 05:15 PM
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ok cleared up I read something entirely different, yes pump in tank accessible without dropping tank... the engine is a 4.0L - I6, inline.

I cannot get connector pinouts tonight will add when I can get to manual.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #6 of 8 Old 02-29-2020, 05:27 PM
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here is why I am having trouble -

the 1996 fuel pump wiriing is not close to what you show in pictures.

That and saturday night ....

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #7 of 8 Old 03-01-2020, 09:18 PM Thread Starter
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@jtec I found another 96 at the junkyard and it had the same wiring in the sending unit's connector?? (minus the mysterious red wire soldered into the connector and running into the engine bay)

Update: cut the old connector (above image) below that weird solder joint. Attached the junkyard connector I got from another '96 XJ to the corresponding wires and plugged the sending unit into the Jeep (after making sure it was actually getting power). Put in the key and the pump had power and sent a good stream of fuel into the cat litter I was using to catch it. After my success, I hooked the fuel line back up, fuel filter, put the sending unit in the tank, and locked the ring.

P.s. using vaseline to keep the rubber gasket in place made the whole process way smoother.

I cranked the engine and it started up strong, the fuel empty light was working now and could actually hear the pump running again. No clicking from the relays this time. I started it a couple times afterwards and let it run a few minutes each time. So far... its working again. Although the fuel rail clicks now but it could have been doing that before. I guess the weird wiring could have caused the short... right? I wish I knew why the OG owner did that... Tomorrow I will drive the thing down the street. Hopefully it doesnt crap out again.
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post #8 of 8 Old 03-07-2020, 07:59 AM
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My thoughts on weird wire...

the jeep 'logic' - the PCM will only supply power to the fuel pump for @2 seconds if the engine does run.
People turn key on then go to fuel pump to check voltage - read above and NO voltage DUH so a wire is added.

guess 2
A wire added because there is an issue with sender/gauge and thinking Add aa wire but its the internal pump portion that has failed....

PS you found a same year jeep - plan a 'scrounge' day and check #s on your and other jeeps PCM;s -

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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