CA-XJ

Hey all,

So since i bought my XJ, my gas gauge has been about a 1/4 tank off at all times. I fill it up and it still says that it is at 3/4 tank of gas. For Christmas I bought myself a new fuel sending unit thinking that it was the floater arm that took a crap. Well, i put it in today, filled my tank, and STILL 1/4 tank off... Cant really think of what else could cause this. Hate this guessing game. Any ideas would help. Thanks guys/gals.

Info: 1991 Jeep Cherokee XJ / 4.0l inline 6 / AW4 tranny

Demonoid369

I'm similar, when I'm on empty, if I add 10-12 gallons it'll show that in pegged full lol I might actually still have a half tank every time I though I was empty lol

CA-XJ

The only difference with mine is that if i put 10-12 gallons in, my gauge will only read at 1/4 tank.

CA-XJ

Anyone?

Demonoid369

Did you at least take the mechanism out and check the ballast swing of motion? Might be stuck and can only go up where it reads 1/4

Ian96XJ

I've read that there is supposedly a ground wire for the gauges and that the stock wiring sucks. I've heard that if you change that ground wire, *all* your gauges will be corrected. I can't verify that myself, but if it's true that there is a ground wire, it could never hurt to ensure a good ground.

cruiser54

Don't know if this applies to your 96, but here it is:



Improving the Instrument Panel Ground

The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release ****. The screw will have either a ¼” or 5/16” head on it.

This ground point is responsible for handling the ground circuit for the following items: Dome lamps, Seatbelt and key warning, trans comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things.

The problem is that where the ground point is located does not have a good contact with the chassis where the ground should be. The solution is simple.

Make up a jumper wire with #10 gauge wire about 10” long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8” round wire terminal.

Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other.

Look above the driver’s side plastic kick panel just forward of the top of the hood release ****. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely.

**Special note for Comanche owners: Make your jumper wire 12” long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.**


Revised 11-29-2011

cruiser54

Here's an interesting link:



http://comancheclub.com/topic/33662-...e-fuel-sender/

CA-XJ

Okay everyone, I'm back at the drawing board. Just now got around to the ground wire, jumped it for a better grounding and nada. So far I've replaced the entire fuel sending unit and made a better ground connection. Any more ideas? Thanks!

Firestorm500

They all do that.

At least my '92 does. My '87 doesn't, but it has the large fuel gauge, where the tach would be if it has the full cluster.

I've given up being OCD about it and just accept it the way it is. I figure it's just Jeep's way of trying to keep their customers from running out of gas by having the gauge read 25% low.

CA-XJ

Haha yeah I guess. I've got the full gauge cluster and that bright yellow light the yells low fuel in my face does seem to get annoying after a while.

gpeade

My 98 is exactly opposite. At 1/4 on the gauge I'm actually running on fumes. Learned that the hard way...twice

Firestorm500

That's good to know if I ever get a '97 or up. If you have one, did the low fuel light come on?

aa7kn

well if you pull out the fuel pump assy. from the tank, you will see the float assembly and on it is a variable resistor. using an ohm meter, ohm the resister, it should read almost a short when the float is all the way up ( full tank) and when it is all the way down ( empty) it is about 107 ohms. also make sure there is no lateral play on the float arm and if there is make sure the ohm readings are all there when you hold the unit on it's right side and left side ( simulating a right and left turn) if need be, remove the resistor and clean and bend the wiper arm a little to ensure a good contact with the resistor coils. also if when you ohm it and it reads correctly, you might need to adjust it, look for a little screw at the top of the coils on the resistor, if you raise up the float, and full take is normally low for you, you need to move the resistor a little to lessen the ohm reading. example IF full take you get a gauge reading of 3/4 tank, you should adjust the resistor to be closer to a short ( less resistance). I had to do this to mine about 3 or 4 times untill I got it set the way I like it. hope this helps

gpeade

Well that's pretty much how I figured I could fix mine. Was unaware of actual adjustments to the resistor but I figured I could just bend the float arm to fool the gauge into being correct. But even with all that...it isn't worth dropping the tank just to do this and I'm not gonna cut a hole in my floor to do it either. Like Firestorm said earlier I have just learned to live with it. If I even HAVE to go in there again I'll do something about it.