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jmeti000

NAXJA Forum User
Location
san antonio,tx
Ive had problems with my fuel system lately. I have gone through 3 airtex pumps (never again). I finally got all my money back and swapped in an oem sending unit and pump. The pump works prefectly....the guage however has issues. Its reading backwards now lol. It says its empty when its full, and full when its empty. Its not like there are wires all over to mess up or anything...the wires all just plug in one way. Anyone know what could cause this cuz I have NO clue :dunno:.
Thanks
jmeti000

oops, forgot to mention its an 87'
 
Nevermind...I know why. I grabbed a sending unit for a 92'. Apparently the guage voltage reads reversed...how stupid can I be lol.

So next question...since my speedo is wacked out anyways, can i just swap in a different guage cluster from say a 91+? I REALLY just dont wanna crawl under there again if I can kill 2 birds with one stone.
 
I'd just use it knowing it's backwards....only due to fear that messing around will only break something else, just tell people the XJ is from Canada
 
No, to my knowledge there is no workaround for the gauge reversal issue.

However, if you want it, there are aftermarket gauges that you could install that read in the Chrylser "reverse" method--AutoMeter has them.
 
The resistance does not seem to be linear. I have the same thing going on (88 MJ sender in a 91 MJ.) Mine says full tank till I have about 1/3 of a tank left and then you can almost watch the needle fall as you drive. Still way better than a fuel leak though!

The RENIX gauge will not bolt into the right location on a 91+ gauge cluster and vice versa, from the info I have (compared bolt patterns on the back of the two gauge clusters.) I may be wrong though, it may work with some modification. I'm still trying to think of a way to solve this, will try to remember to update this thread if I do.
 
Ive had problems with my fuel system lately. I have gone through 3 airtex pumps (never again). I finally got all my money back and swapped in an oem sending unit and pump. The pump works prefectly....the guage however has issues. Its reading backwards now lol. It says its empty when its full, and full when its empty. Its not like there are wires all over to mess up or anything...the wires all just plug in one way. Anyone know what could cause this cuz I have NO clue :dunno:.
Thanks
jmeti000

oops, forgot to mention its an 87'

i know the airtex pump i put in my 89 had the positive and negative terminals on the opposite sides then on the oem pump. i remember having to be careful not to reverse the polarity of the pump.

did you happen to notice if this was the case with the aitex pumps you installed?
 
Could the problem with the Airtex pumps short life be a design error--what I mean is if Airtex pumps are designed for sustained operation at reduced voltage, like the 87-93s with the ballast resistor, they might not last long in XJs that have the ballast resistor bypassed or in the 94+ without a ballast resistor?

Just spit-balling.
 
The HO gauge cluster has electric speedo, and the RENIX gauge cluster has a mech speedo cable.. therefore the gauge cluster will not swap. Unless you do not want a speedo anymore.
 
I was talking about just the fuel gauge itself - and yeah, the gauge cluster won't swap unless you want to swap your VSS as well (and add a mechanical speedo cable), which may or may not make the ECU angry. I suppose you could build an adapter to make the ECU read off the OSS instead assuming you have an AW-4.
 
OK...just FYI, you CAN swap the fuel guage out of the HO to your renix...but it takes a little modification....sooooo this might have to be moved to the mod thread. Unfortunately I didn't get any pics of the process, but its pretty straight forward.

Step 1...Lets not avoid the obvious and get the gauge from a HO vehicle.

2. After you remove the cluster in your dash, unscrew the tach, fuel gauge, and the little circuit board located directly underneath the tach.

3. Remove the little gauge light (will be in the way of the circuit board for the new fuel gauge), and break off the little barrier wall enough so the circuit board from the new gauge will fit across.

4. Break out the solder gun, exacto knife, and 3 pieces of wire about 6" in length. If you look on the new and old circuit boards, you will see where in says acc, ground, and unit on each. With your exacto knife, CAREFULLY scrape off the plastic from the copper leads on the back of the gauge unit to each of these leads, and solder the wires to the copper (It attaches just fine, but I put a tad bit of super glue over the connection just to be sure...since im not the most graceful person).

5. On the new fuel gauge, attach the other end of the wires to the corresponding whole. I just rethreaded the screws into the board and wrapped the wire around it before snugging it down.

6. Screw the new fuel gauge back in (it fits into the existing holes perfectly).

7. Reinstall the tachometer

8. Put the cluster back into your vehicle, hook it up...and VOILA!!! The fuel gauge now reads correctly for fuel pumps from HO vehicles 91-96'.

Not that anyone will need this, but just in case someone makes the same mistake I did there you have it.

cheers :)
 
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Damn fine answer to a problem and a good write up. There have been a number of others having the gauge issue because they upgraded(?) to the plastic fuel tank! Nice job.
 
That is awesome, thanks! I saw that there were 4 terminals on one and 3 on the other and that they didn't line up, and said "this is a project for another day", I must have miscounted or something.

That info is a LOT of use to the MJ crowd, as MJ fuel senders are a junkyard only type of part (no one makes them) so you use whatever you can get and live with it. GREAT writeup!

:cheers:
 
actually you are correct kastein....there are 4 terminals on one and 3 on the other. The terminal position for the "out" connection will not be used for this mod. The only thing that terminal does is provide the power for the low fuel warning light. On the new gauges the warning light is integrated in already so there is no need to use that terminal.
 
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