Inline6FourPointO

Just put 35.00 in gas got about 10 gallons. Now my gas gauge is going up and down.

Anony

When the fuel gauge begins to read too high or too low, usually means the fuel gauge sending unit is faulty.

The fuel gauge starts to read off, eventually behaves erratically and sometimes stops working altogether.

As the fuel gauge sending unit condition worsens it may cause drive ability and sometimes starting problems. Later years XJs the fuel gauge sending unit is monitored by the PCM to control the fuel gauge, run the evap. system and other engine functions

All that's usually required to remedy fuel ga. and related problems is to replace or repair the fuel gauge sending unit.

You also might want to inspect the wires and connections to the fuel gauge sending unit. 97+ XJs the fuel pump module inside the fuel tank includes the fuel filter/regulator, fuel ga. sending unit & fuel pump.

MikeTassjeep10

Could it be the float in your gas tank? My gauge fluctuates when I turn and stop. Little less little more. Float in the tank

Anony

Not normally, the float doesn't usually change from its original set position in relation to the fuel ga. sending unit.

A more common problem is the fuel gauge sending unit starts to wear from age and use.

What often happens after age and use the fuel ga. sending unit all of sudden begins to effect operations of the fuel gauge. (later model XJs the PCM monitors the fuel gauge sending unit and controls the fuel ga. and perform other PCM functions, such as the evap system, and other program logic events.)

I let mine go for a while. The Jeep started to have intermittent problems while running and sometimes while starting.

After replacing the fuel ga. sending unit the problems went away.

DELRUS

I had to post this here because I had a crazy fuel gauge thing happen to me.
I'm aware it's probably the sending unti going out but crazy no matter.
I filled up and had maybe 20 miles knocked off the top of the tank so far, so my
gauge was just barely below the F line. I stopped and was talking to a buddy window
to window and sitting idling. Talked about 15 minutes and all the sudden I hear the fuel
low light go off, look down and the gauge was on E. So I got out thinking I just dropped a
fuel tank of gas on the ground somewhere. Nothing leaking so I figured the sending unit
just died. I shook the jeep and did the ole pump brake shake to see if I could get the
gauge working again, but no. So then I thought let me turn it off and back on to see
what it does. Turned the jeep off let it sit for a minute and then when I turned it back
on it came right back up to where it was before like normal.

So after this I think I'll be dropping the tank and replacing the sending unit.
If and when I do this, I'll add pics and procedure to the thread!

Klutch

What year is your XJ? I ask because I owned a 1997 XJ for forteen years and in almost all those years it had a flakey fuel gauge. When I filled the tank, it would work, then it wouldn't work. When the gauge got to around 1/2 tank, it would stay working again; until the next fill-up.

Chrysler actually issued a recall for this problem. I printed out the recall and took it and my Jeep to the local dealer. They pulled up my VIN and confidently proclaimed, "This recall covers vehicles manufactured through June. Yours was manufactured in July, so you don't have the problem."

I explained sitting in my Jeep for 30 seconds with the key on would clearly reveal my Jeep DOES have the fuel gauge problem. Their distopyian reply continued to be, "Your vehicle does not have this problem".

Thus, I'm thinking your XJ has this problem. If it's within the recall, Jeep is required to fix it free of charge. Thus, I would suggest you look for fuel gauge recalls and check your VIN. Maybe you'll get lucky and find yours actually has the problem according to Jeep.

extrashaky

I was driving along through Arkansas with about 3/4 of a tank when motion on the dash suddenly caught my attention, and I glanced down just in time to see the fuel needle sweep all the way to E just before the light came on. I had the same reaction you did, thinking I must have just dumped all my fuel. When I didn't see any fuel under the truck, I turned it off and cranked it again, and the gauge has worked just fine since then. That was two years and 20K miles ago.

I kept a close watch on it for a while, but eventually, when it didn't do it again, I forgot about it until reading this thread. I'm not going to worry about it until it makes itself a problem.

kdot

Mine does this too..but only when I have a full tank or recently full..

Turbo X_J

Ignition switch / connector.

jeepdiy

Could you post a copy of this recall?

Klutch

ID Number: 97V194000
Component: fuel: fuel tank assembly: gauge: fuel
Potential Number of Units Affected: 209,000
Year: 1997
Manufactured From: Jul 1996 To: Jun 1997
Year of Recall: '97
Summary: Vehicle Description: Multi-purpose passenger vehicles. The fuel tank mounted fuel level sending unit accuracy can degrade over time, indicating significantly more fuel in reserve than is actually present. Owners may not be aware that their vehicle is low on fuel increasing the risk of a vehicle crash if the vehicle stops due to no fuel.