Fuel Gauge Problem

Billy M · **Posted:** Mon Jan 20, 2014 11:33 am

Long story short...I ran out of fuel over the weekend with my gauge reading 3/4 full. I put 5 gallons of fuel in it, primed it, it started right up. I drove to the gas station and put 14.2 gallons of fuel in it to top it off. Definitely was empty. The gauge went back to "full" when I put the 5 gallons in it, so there was no change at the gauge when I filled it up. I've driven almost 150 miles since and it's still showing "full". It's still jacked. It usually comes off of "full" around 90 or 100 miles on a good tank. The gauge goes to "empty" when I turn the key off. The gauge itself appears to be working fine. For now, I'm assuming it's the sending unit.

Anyone else run into this? Any suggestions before I start diagnosing? Would a pinched/grounded wire cause this? Thanks.

Billy

papaindigo · **Posted:** Mon Jan 20, 2014 12:10 pm

Yep both I and stoutdog experienced similar symptoms; fuel gauge reading way too high and otherwise erratic. In both cases a new battery fixed the problem.

Billy M · **Posted:** Mon Jan 20, 2014 2:32 pm

Interesting...I put a new battery in it in February 2013. It's not even a year old. It has cranked/started fine in the below 0 temps we've recently had. Do you think a disconnect/reconnect of the battery may fix it? I doubt this battery will test bad for a warranty replacement. I'll try a disconnect/reconnect and see what happens. I could get the battery tested while I'm at it. Thanks for the input.

I'm open to other suggestions in case this doesn't fix the issue.

Billy

papaindigo · **Posted:** Mon Jan 20, 2014 2:48 pm

I'd do a disconnect/reconnect; a good cleaning of the battery terminals; check the ground connections; have the battery load tested and alternator output tested by some reputable place OTHER THAN the place that you got the battery from just in case.

In our situation (my 05 and his 06) we were on relatively old red tops that were still working but at least in my case cranking a bit slow in like 25F temps. His was still cranking fine (Tempe, AZ) but his fuel gauge readings went nuts and I suggested a new battery was worth a try since it was time anyway. In my case the fuel gauge problems stopped as soon as the new battery was in. In his case the gauge was "less odd" for a month or so and then settled down to normal.

No clue why.

IIRC the FSM has a method to test the sending unit but I'll bet you have to drop the tank to do it and even then it could be a bad float. I seem to remember someone having a float come loose problem.

mass-hole · **Posted:** Mon Jan 20, 2014 3:22 pm

papaindigo wrote:

Yep both I and stoutdog experienced similar symptoms; fuel gauge reading way too high and otherwise erratic. In both cases a new battery fixed the problem.

That's like when the tranmission on my Lincoln LS was letting go on the freeway and coasting because one of the Coil-on-plugs was causing an undetectable misfire(no CEL or noticeable stuttering of the motor). The whole time I thought the transmission was going and then I swapped the coils while doing a valve cover gasket and the car was good as new.

Billy M · **Posted:** Mon Jan 20, 2014 4:44 pm

Thanks. I'll give the disconnect/reconnect a try. I'll load test the battery while I'm at it. The alternator was replaced with the battery due to the decoupler. The old battery was still working, I just wanted a fresh electrical supply. I'll also check the alternator while I'm at it, just to be safe. I'll report my results.

Billy

Billy M · **Posted:** Tue Jan 21, 2014 3:33 pm

Well...alternator and battery checked out fine. I disconnected, waited, and reconnected the battery. No change in the fuel gauge. I guess I have some checking to do once the weather warms up. Anyone here worked on the tank/sending unit? Anything special to look out for while dropping the tank? Thanks.

Billy

papaindigo · **Posted:** Tue Jan 21, 2014 4:42 pm

Search the PDF version of the 06 FSM for "fuel gauge" for some diagnostic suggestions before dropping the tank. As for dropping the tank if no one volunteers hints send me an email, not a PM, and I'll send you text from an old post for which I lack the link although there might be comments buried in the long string at viewtopic.php?t=26385&highlight=

Billy M · **Posted:** Thu Jan 23, 2014 1:49 pm

Hmmm...I didn't find any procedures in the FSM, but did find some values to check at the plug, which may require dropping the tank. I thought about replacing the sending unit if I dropped the tank since they aren't that expensive. To add to my frustration, the sending unit is only sold as a cartridge assembly available only at the stealership. Scuttlebutt has it, the sending unit is the same as the gasser. The gasser sending unit is sold as a cartridge assembly also, fuel pump included, so no savings there. Does anyone have any insight on a "sending unit only" part number? If not, I'll be verifying that the sending unit is bad before ordering (if needed). Of course the CRD sending unit is an order only part. 3-4 days out. It will probably be a while before I tackle diagnostics. It's fairly cold here in southern Ohio. I'll post my findings in the spring. =) Thanks for all the suggestions.

Billy

bugnout · **Posted:** Fri Jan 24, 2014 4:35 pm

I dropped the tank when I installed the in-tank lift pump a few years ago. Isn't difficult, I dropped it and had it back together in an afternoon (6 hours). Lots of good info on what you'll encounter in this thread

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=26385&start=0

Is that New Carlisle or just Carlisle OH? I was stationed at Wright-Patt for 12 years. I think New Carlisle is North of Dayton and Carlisle is South of Dayton.

Billy M · **Posted:** Mon Feb 03, 2014 2:20 pm

Update...I got off work last Thursday and the fuel gauge was working!?? It was showing around a 1/2 tank, right where it should have been from the miles driven. I filled the tank on Friday, the gauge went to full. I always fill the tank, not topping it off. A full tank is nothing new for the gauge. I drove it a lot over the weekend. The gauge has gone down as it should with the miles driven. The gauge appears to be working as it should. I can only guess the float/arm was stuck in the "full" position. I didn't hit any unusual bumps on the way to work or anything. I have no good reason for it to start working again.?? I'll take it. We'll see if it lasts. I have all the info I need in case I need to drop the tank in the future. Hopefully I don't have to! Thank you all for the help/info.

Bugnout...I'm in the Carlisle south of Dayton. That is normal confusion, for even locals, when I tell people what city I live in. I have a buddy that's a civilian employee at Wright-Patt and I've done some construction-related work there. If you were stationed there a while back, the area has changed a lot (outside the base). The Fairborn/Beavercreek area has been a busy construction area for a while now.

Billy

Fuel Gauge Problem

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