Fuel Gauge not working...any suggestions?

Hello all, :wave1:

I recently had a new fuel pump put in my 90 4.0L XJ and my fuel gauge is not working. I took it back to the shop that installed and they supposedly checked it out with another gauge which worked so they thought it was my gauge.

I went to the junkyard and got 2 fuel gauges from a 90 and an 88 XJ. I pulled out my instrument cluster and installed them and nothing....the gauge goes all the way past Full to horizontal! I pulled the connector from the sending unit and it did not go to Full as it should, and then I read an Alldata that the harness wires #15 and 17 should read 0-88 ohms and it did. The only thing I can think now is that the plastic circuit board thing on the back of the cluster is bad.

I am thinking about taking it to the dealer but that could be $$$$$. I have also contemplated getting a whole cluster from another rig and trying that.

Any suggestions would be appreciated.

Thanks,

LTK

i would price out a new one, if there available, and price out a used cluster, and go from there

I believe that there was a change made, in some year, so that the sender/guage resistance works in the opposite direction.


They may have put in a pump with a newer sender, which is causing your problem.

There is a thread .... on here...that discusses this.



And here it is .....

Get a guage from a 91 and up.

Thanks Lou,

I checked out that link. Do you think it would be a good idea to just try to get a fule pump from a 90 or earlier XJ and put that in?

I have never installed a fuel pump and am a little leery of doing something I have not done before. But then again if I can find one at the JY I will have at least uninstalled one.

Thanks,

LTK

On your year, is the fuel pump inside of the tank?
That one is:
*expensive
*hard to change (you got to drain the tank)
*a mess because of all the smelly and hazardous gasoline fumes

Does the sender work? When it is full the sender should be 0 ohms or grounded. When it is empty, ohms are high. Then the variable resistor should read somewhere in the middle at half.

Why don't you use a custom aftermarket custom gage, like a moon or VDO or AutoMeter? Mite look "Kul" too (you can just blank out the other one).

I actually want to keep the original gauge. I am thinking about going to the junkyard to take one out as practice. The post here referenced a change in the 91+XJ that changed the polarity of the sending unit which might be the problem.

Maybe I will wait unitl I get low on gas to change it.

LTK

You have a new pump in there--I would definitely not put a used one in its place.


Just to make sure that your problem doesn't lie elsewhere....

Even with the wrong sender/guage combo, it should be able to indicate 1/2 full somewhat correctly. Does it?

It the tank is still pretty full, try driving up a steep hill -- the fuel guage should move towards Full a bit.




Ultimately, the garage put in the wrong pump -- it is their responsibility. They got it close, but they didn't get it completely right.

Do a search on a carparts site --see if there are different pump assemblies for the different years.

No it does not respond at all. It consistently goes to past full to hold at 90 dergrees.

On the link you gave me it mentioned that I could swithc the wires from the sending unit....would that be worth a try?

I guess I could also test the resistance at the connector coming from the pump as well.

I might need to get a little angry at the shop and have them fix it!

LTK

I checked the connectors coming out of the fuel pump and I got a reading of 1.5 ohms which I believe tells me that it is the post-91 fuel sender. It should have read 0-88 if is was correct. I am going to drive around some and see if that value changes and if it does I know it is working but is the wrong sender hence my gauge problem.

LTK

one-point-five does not sound right.

You should have a reading of 5(full) to 105(empty).

Well I did it! :yap: Went to the junkyard to do some research and found a number of fuel senders hanging out of old XJ'a and a couple still in the tank. removed three of them, 2 still had new looking pumps. I bought a sender and a complete set up for $49 and went home to test these that were both pulled from a 90 and an 88 XJ.

Success! The Fuel Gauge worked.

Now I needed to unisnstall mine and see what was up. Luckily the practice at the yard helped a ton!

As I am pulling it out I noticed that the plastic housing of the sender unit is disconnected from the fuel sender metal body. As I was extracting the whole unit from the tank the filter boot fell in the tank! Damn! Hands too big to get in fuel pump hole. Lower the tank to get it out.

Few hours later...after testing it a few times.....reinstalled and voila....gauge works!

Thanks for all of your advice,

LTK