Fuel Guage

[dksob81]

on my 98 ZJ 5.9Limited, the fuel guage is going wacky. the day before yesterday when I came home from running around I had 1/8 of a tank, then when I left to go to work yesterday morn the gas light was on and it was empty. I got to work and turn the key ON for a few seconds then off, I did this about 10-15 times and then my gas guage went up to just a lil under 1/4 tank. This has happened a few times since I went wheelin' (1 1/2 weeks ago).

Does anyone have any clues on what the problem could be.

[sreilly77]

Originally Posted by dksob81

on my 98 ZJ 5.9Limited, the fuel guage is going wacky. the day before yesterday when I came home from running around I had 1/8 of a tank, then when I left to go to work yesterday morn the gas light was on and it was empty. I got to work and turn the key ON for a few seconds then off, I did this about 10-15 times and then my gas guage went up to just a lil under 1/4 tank. This has happened a few times since I went wheelin' (1 1/2 weeks ago).

Does anyone have any clues on what the problem could be.

I don't know but I have the same problem. Today I left for work and the gas gauge was right at 1/4 of a tank and when i left it was a little less than 1/4 (which I thought was because i was parked on a hill). then when i came home and went back out it was almost on Empty. I don't get it. I think may be it is a broke baffle in the tank and the float might be floating freely? I don't know...

[Bob D.]

Originally Posted by dksob81

I got to work and turn the key ON for a few seconds then off, I did this about 10-15 times and then my gas guage went up to just a lil under 1/4 tank.

This sounds more like an electrical issue rather than a mechanical one.
Maybe check the ground of the sensor, or even the battery.

The gauges are dampened by fuel tank baffles, mechanical float dampers, and I believe by electronically damping the voltage changes to the gauge.

In my experience fuel gauges get more unreliable the older the vehicle gets.

[dksob81]

Well it says in the FSM that "if the PCM detects a short or open it will tell the BCM to set the fuel guage at EMPTY Stop".

[Bob D.]

Originally Posted by dksob81

Well it says in the FSM that "if the PCM detects a short or open it will tell the BCM to set the fuel guage at EMPTY Stop".

I didn't mean to imply that it had a dead short or full open, only that it might have a flakey ground, just enough to cause voltage fluctuations that would make the gauge slightly erratic.

[dksob81]

This started when I went wheelin' a couple weeks ago. but the thing is it only does it when it is around 1/4 tank or less, like it won't do it if there is 1/2 tank or anything just when it is low. and I never noticed it before then. Well let me tell the whole story of the first time.

I went wheelin on a friday was out for a couple hours got stuck once a friend pulled me out. went home, went to work saturday and came home from work and order some food went to go pick it up and the jeep wouldn't start, I immediately looked at the headlight switch thinking I left the headlights on, but I didn't tried to start again nothing just a single click then that went away after another attempt I had nothing like the battery was completely dead. So I tested the battery and it was still good, so it had to be the starter, got under the jeep tapped the starter with a hammer and it started right up. got the food came home, then about an hour or so later my aunt called she locked her keys in her car, So I had to go help her, again the jeep wouldn't start had to tap it with a hammer and it started. went to help my aunt and left the jeep running the entire time (maybe 30 minutes at most), I went to turn around and when I was backing up it stalled, then wouldn't start again so I had to tap the starter and then feather the gas pedal a lil bit and I was like WTF I never had a problem with stalling in this jeep, Well when I was getting ready to leave the parking lot the wifey seen the fuel guage light was on and I was on 'E', again WTF it had a hair over 1/2 tank yesterday b4 I went wheelin ( I know this because on my way there I was alomost by a truck stop and was goig to fill up but then I looked and seen I had 1/2 tank so decided I would get some later) So I went home I was gonna have the wife have her father take her to get some gas (my overhead consol read 0 miles left) for me, but he wasn't home, I decided to wait until the next day (sunday) because I was gonna replace the starter anyways because I had one from my old jeep. B4 I replaced the starter I made sure I was getting power to both terminal constant and switched, OK, so I replaced it. After replacing it I started the jeep a few times and looked and noticed I had 1/8 a tank of gas, humm thats wierd. So I let the jeep sit for about 20 minutes while I went and got changed, came out to run to the bank and then go get some gas, started the jeep (started just fine) was backing out of the drive and the fuel guage light was on (guage read empty), WTF pulled back in was gonna have her dad take her to get some gas, just playing with the key turning it ON and OFF (while waiting for her) and after about 5 times or so the guage started to rise up to almost 1/4 tank. I told her never mind and went and got some gas. and I have had this problem quite a few times in the last 2 weeks. but it won't drop down real far (say from 1/2 to E) only around 1/4 or less.

[Bob D.]

Just a thought -- next time this happens, get under the fuel tank and give it (the bottom of the fuel tank) a couple sharp thumps with your fist, maybe the float is sticking.

[sreilly77]

Originally Posted by Bob D.

Just a thought -- next time this happens, get under the fuel tank and give it (the bottom of the fuel tank) a couple sharp thumps with your fist, maybe the float is sticking.

hmm good idea...i only ever did that if the fuel pump was bad but that makes sense. i'll give it a try

[dksob81]

I tried tapping on the bottom of the gas tank but did not change the reading on the guage. Any other suggestions?