Fixing the Fuel Gauge on an '89

[Nevada City Sparky]

I just got thru restoring my 89 w/ 4.0L and Automatic. One of the remaining "gremlins" is that my fuel gauge is pegged at 3 o-clock. I replaced my fuel pump with a unit I got from NAPA (Bosch, I think) and I suspect, from my searching, that it has the wrong sender unit in it and is probably working backwards. So it sounds like I have 3 options:

1. Swap the ground and sender wire on the fuel pump harness
2. Swap in a later gauge from a 91+ into the cluster
3. Pull the pump and swap in he old sender.

Of the three choice, #1 is the most appealing since I REALLY dont want to pull the pump yet again. Returning the pump probably isn't a good option either since I'm not sure I can find the receipt and I bought it several months ago.

What would you do?

[90xj06]

make sure the wire comming from the sender is infact good and is connected to the gauge.

[Nevada City Sparky]

Well, yeah. Been thee, done that. Wiring is quite intact, having been gone through during the restoration.

So, any answers to the above?

[jeepdude10000]

im guessing the tank is full if it is working backwards, mine has been backwards since i bought it, i dount worry about it.

But if ur worried, did u change the sender, and if u did one from a newer model would make the gauge work backwards.

[Nevada City Sparky]

im guessing the tank is full if it is working backwards, mine has been backwards since i bought it, i dount worry about it.

But if ur worried, did u change the sender, and if u did one from a newer model would make the gauge work backwards.
Did you read what I wrote? Yes, I changed sender and fuel pump (as a unit). I suspect from reading searched posts that it has the later style sender. Just trying to figure out if switching the two ground wires will fix it. The guage reads super-full all the time, which would make sense if its getting full ground.

[jeepdude10000]

im thinking of changing the gauge conections on the back, wonder if that will work?

[Nevada City Sparky]

im thinking of changing the gauge conections on the back, wonder if that will work?
Well, I'm hoping that someone with a bit more knowledge than you or me will pipe up. It would make more sense to switch the wires at the sender, rather than the gauge. Gonna wait for a real answer B4 I attempt.

[Lou]

I have not looked at the internals of the pump assembly, but by what the schematic in the FSM would indicate, solution #1 would not be feasable.

Swapping wires externally(to the pump/tank) should not be a doable solution. Eagle has stated otherwise -- so, may it is. :dunno:

If the guage is pegged at 3 o'clock(full), then you have a bad(open) connection somewhere.

[Nevada City Sparky]

I have not looked at the internals of the pump assembly, but by what the schematic in the FSM would indicate, solution #1 would not be feasable.

Swapping wires externally(to the pump/tank) should not be a doable solution. Eagle has stated otherwise -- so, may it is. :dunno:

If the guage is pegged at 3 o'clock(full), then you have a bad(open) connection somewhere.

Well, there's about a foot of wires coming outta the tank, its easy to swap. Don't think I have an open circuit. The gauge worked B4 I replaced the pump/sender unit.

[Lou]

Two things you could try, first, disconnect the pump assembly from the harness connector;

1) on the harness to the guage, short out the center contact(DARK BLUE) to ground(BLACK). Did the guage needle move?

2) If you have a meter, measure the resistance between DARK BLUE and BLACK on the pump side of the harness/connector.

[Nevada City Sparky]

Thanks Lou, I checked that, the sender is good, just from a later model Xj where (I think) the wires are reversed. I just wasnt sure if Ohm spec was the same, or close enuf that a wire swap would work.

[Nevada City Sparky]

this is a bump, hoping someone can answer the original questions.

[jeepdude10000]

here is a link to another post that also had problems with fuel gauge.

http://www.naxja.org/forum/showthread.php?t=85170&highlight=fuel+gauge

[Nevada City Sparky]

here is a link to another post that also had problems with fuel gauge.

http://www.naxja.org/forum/showthread.php?t=85170&highlight=fuel+gauge
Yeah, I found that link. Wanted confirmation if true that reversing wires would work, before I start hacking on a new part.

[Bounty Hunter]

Need to know this myself, didn't want to go messing with the wiring going into gasoline unless I know it can be done safely.

My truck is an '88, and the fuel pump/sending unit is from a '91, and did the gauge swap.

[90xjDave]

I had the same problem with my '90 when I swapped a tank from a '95. Switching the wiring didn't work. I had to go back to my original pump to get my fuel gauge to read correctly.