YJ gas gauge s(t)uck

So I realize YJ gas gauges are notorious for sucking and being inaccurate, and I was ok with having a 15 gallon sending unit for a 20 gallon tank and just having it be on "F" for the first 100 miles, but since November or so, it's been getting stuck at half a tank until I fill it back up again and I'm starting to get annoyed at it.

So you other YJ owners (probably more specifically the 92+), does your gas gauge go back to empty when you turn off the Jeep? Or does it stay at the same level? I'll check when I get home, but I think mine stays, which if not usual, would point towards the gauge being the problem.

I'm hoping it's just the gauge and it needs a bit of cleaning, because I really hate dropping the tank, and really am not sure it's worth the $250 to replace it if it's the sending unit.

I'm not sure how those work but on some vehicles if you ground out the neg wire to sending unit with key on and it goes to full it is the sender that is at fault and not the guage..
I think that is how you do it.
Do that search before you do what I said to do I can't remember getting old.... LOL....

A somewhat common problem is the "cup" in the bottom of the fuel tank will warp over time
It's a white plastic cup that's intended to keep some gas around the fuel pickup screen when you are momentarily are off camber or making a tight turn. What happen is the gasoline over time can cause the side of the "cup" to warp and bow out causing the float from dropping all the way as the gas level gets low. Typically the gauge will stop at around 1/4 of a tank.
You can...
- Live with it...
- Drop the tank and bend the float arm so it doesn't hit the wapred cup
- Drop the tank and cut the warped side of the cup away.

Found this on yjs but I would do the ground test first.

Awesome Mark, thank you!

I had heard something about it rubbing on the cup, but it hadn't made any sense. This is a much better explanation.

It used to happen at like 1/8th of a tank, then 1/4, now 1/2, so I'm guessing that's probably the most likely cause.

I'll probably check grounds and clean up the gauges anyhow because it probably needs it after 18 years, but when I get a free weekend I'll definitely be checking the float arm!

Good luck with the yj Geoff.
Hope things are going well for you in Texas, I missed any send off party you may have had.
Mark,,

The fuel gauge shouldn't go back to E, but I think you may have that cleared up already. When I had the new sending unit installed I know the float needed to be adjusted because it would only fill to 7/8 and nothing more. Before the new sending unit was installed the gauge didn't work under half a tank period, but my previous car was the same way so I had gotten used to that. My gauge does have a tendency to slowly move from F to half now, making me think my mileage is great, and then dive-bomb from there.

I will also say that when I get to E I generally have at least two gallons of gas left, maybe more, but I'm not sure if you've had the same experience with that Geoff. I've been lulled into a false sense of security now that my gauge 'works' though because twice in the last five months I've run out of gas, so once again I'm back to counting miles.

THOOPY3 wrote:The fuel gauge shouldn't go back to E, but I think you may have that cleared up already. When I had the new sending unit installed I know the float needed to be adjusted because it would only fill to 7/8 and nothing more. Before the new sending unit was installed the gauge didn't work under half a tank period, but my previous car was the same way so I had gotten used to that. My gauge does have a tendency to slowly move from F to half now, making me think my mileage is great, and then dive-bomb from there.

I will also say that when I get to E I generally have at least two gallons of gas left, maybe more, but I'm not sure if you've had the same experience with that Geoff. I've been lulled into a false sense of security now that my gauge 'works' though because twice in the last five months I've run out of gas, so once again I'm back to counting miles.

Ha ha ha, I think that is a pretty perfect summation of YJ gas gauges.

I'm definitely going to have to take a lot of pictures and document it when I finally do pull it, in hopes of making the unit and symptoms a bit clearer for someone else some day.

To clarify, the gauge did work under half a tank with the old sending unit, but it had 0% accuracy is all. It would eventually get to E but it wouldn't do so until I was pretty much out of gas. I realized my last post might have made it sound like the sending unit is your issue, wasn't my intention. Your issue is a little different than mine was.

I've got 4 gallons left when the E light comes on. This was officially documented when I ran the tank completely empty (jerry can in the back) and got 325 miles out of my tank, for a whopping 17.1 MPGs. Highway and city combined.

There's hope out there folks. Miles and miles after the Empty light comes on.

Now that I knew what to google, I found a good article on sending unit and the "cup".

http://www.neow.net/yjgasgauge.html

Dude bent his sending unit. I'd rather just rip the little cup out.

Also found this an an explanation of cleaning up any corrosion on the dash.

http://www.jeepforum.com/forum/f12/repair-w-pix-stock-gauge-cluster-how-991307/

Whatever you end up doing Geoff, I hope that it works out without a hassle.