• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

1996 XJ fuel pump and pressure regulator repair details

Wiring:
On our 96:
1: Dark Green/Red = Fuel Pump Relay Output(+12V)
2: Black/Light Blue = Sensor Ground
3: Dark Blue = Fuel Level Sensor Signal
4: ----------
5: Dark Blue/White = Low Fuel Sense
6: Black = Ground

On 97+:
1: Dark Green/White = Fuel Pump Relay Output
2: ---------
3: Dark Blue/Light Green = Fuel Level Sensor
4: Brown/Yellow = Sensor Ground
5: ---------
6: Black = Ground

You have to move pin 4 from 97+ fuel pump tail to pin 2 and I haven't done anything with the Low Fuel Sense yet(don't really care about the low-fuel light on the dash).
 
Except for moving some of the wire pins, it sounds like it's almost a straight swap, yes?
No cutting of sheet metal? No welding? If so, then this is on my "To Do" list. I am
always a bit nervous about having the fuel pump on my '96 to go south on me while out
in the boonies - and then having to hunt for another rare and expensive fuel pump.
 
I replaced my 96's bad pump with a $70 walbro and it worked fine(but whined more than the stock one). I put 6+ gallons in yesterday and the needle hasn't moved, so don't follow me down this path yet. . .
Oh yeah, the colors I mentioned above for the 99 are the body harness colors and not the actual fuel pump tail colors. Besides the +12v and Black ground that get the pump going, there is a pink with black wire and a black with green wire. I swapped them between pins 2&3 and no change in gauge. At least I know the stroker is consistent with its 15mpg city. . .
 
Last edited:
Sorting through the details is the fun part. :looney:

A working fuel gauge is a priority if I ever decide to go down that route. Let us know if you find a solution.
 
So the gauge goes from 1/4@full tank to 1/4 below the empty. Maybe I'll measure the resistance of the old float full swing and compare to new float.
 
Sounds like the sender got bumped. The older style use a strip with contacts, and as the arm moves it sweeps across the contacts. The jeep senders are pretty robust so it usually has to physically dislodge (unlike my old Cadillac which uses thin strand wire (folicles) that simply corrode and break.)
 
The prob is that the '96 and under senders are different than the newer dash '97 and newers, so don't know yet if it's a resistance difference or has to do with the dif protocol.
On a side note, my Jeep kicked @$$ yesterday in autocross and weighs 2700# wet and didn't have a metal tank with a loose baffle in it.
 
Last edited:
Adding to old thread, when I bumped mine, it was a bad connection. I cleaned all connections, checked unit to gauge plugged in, outside of tank, and then reassembled.

I was pretty irked to find it didn't work the first time. No reason not to pull the slip terminals and clean the tabs while you're in there. Mine were crusty and obviously needed to be cleaned.
 
Hi all,

New to this site and this thread is very relative to what I'm trying to achieve at the moment. Has anyone had any headway with the getting the fuel guage to respond correctly?

Thanks

Sean
 
I was curious, and decided to make the $30 contribution to science.

What you get is the approximately 1" x 2" wafer that the fuel arm sweeps across. It certainly isn't going to help anybody who has a fuel delivery problem unless they can't keep track of when their tank is full or empty.

That said, it does pose some questions for me, particularly about the possibility of modifying a '97+ or ZJ tank and sending unit for use in the '96. Those units will fit, but pose a problem with the fuel gauge. To my knowledge no one has managed to figure out how to get them to talk with the '96 and down fuel gauge.

Now I just need to get my hands on a late model fuel pump/sending unit module and see what it would take to modify that. This little wafer might be the key to success.
 
Here is what you get if you order that $30 fuel sending unit:

XJFuelSendingUnitOPT.jpg


Note that is the actual piece in the lower right hand corner. For the sake of scale, instructions are printed on a standard 8 1/2" x 11" sheet of paper. I simply placed the "sending unit" and the sheet of paper on the scanner.

There is my contribution to science for the year.
 
I just measured the 96's fuel sender resistance: 1.1K ohms empty to 100 ohms full.
4087c3cce6cec029c1a1408904b3ccbc.jpg
abeb599ad24307f92ca1639bdeb6b43b.jpg



Sent from my iPhone using Tapatalk
 
Here is what you get if you order that $30 fuel sending unit:

XJFuelSendingUnitOPT.jpg


Note that is the actual piece in the lower right hand corner. For the sake of scale, instructions are printed on a standard 8 1/2" x 11" sheet of paper. I simply placed the "sending unit" and the sheet of paper on the scanner.

There is my contribution to science for the year.

did-we-just-become-best-friends.gif


You are the freaking BOMB! Pretty much any time I've had a question about my 96, you've pretty much had a thread on it LOL!

I feel like we should start a 96 XJ owner thread so we can compile a list of our findings all in one spot!

Sorry for the thread derail and thank you for your contribution to SCIENCE! :)
 
:cheers:

You are quite welcome.

I figure the '96s get a bad rap because they are unique and idiosyncratic.

For better or worse the same attributes apply to me.

I have to do my part just as a matter of self-interest.

:cool:
 
Geoff added some useful info over in Modified Tech that might be worthwhile to someone else perusing this thread:

1987 - 1990 XJ
Empty 1 ohm
1/2 44 ohm
Full 88 ohmSource: 1989 FSM

1991 - 1996 XJ

Empty 105 ohm
1/2 33 ohm
Full 5 ohm
Source: 1993, 1995, 1996 FSM.

1997 - 2001 XJ
Float down 270 ohm
Float up 20 ohm
Note: This may not be the actual full and empty positions. The 1997 - 2001 FSMs do not lay the resistance values out the same as the earlier ones.
Source: 1999, 2000, 2001 FSM

ZJ

The only ZJ book I have is 1993:
Empty 105 ohm
1/2 32.5 ohm
Full 5 ohm

ZJ tanks seem to be an easy swap, and if the sending unit speaks the same language that may be a lifesaver for someone who can't come up with the right parts to keep their '96 fuel system operational.

And yes, I know it is a modification, but I think it is relevant to this thread.

Relevant Modified Tech thread: http://www.naxja.org/forum/showthread.php?t=1123236
 
Yes, apparently I measured wrong, so disregard the resistance values I measured(already said that in other thread).


Sent from my iPhone using Tapatalk
 
Hi , just on the fuel pump , discovered today that my Alternator sometimes drops under 12 volts , I think this could be the reason for my Jeep's , surging/cutting out , what would be minimum volts to keep the pump running ? , cheers.
 
Back
Top