Gas gauge

Has anyone ever had a problem with their gas gauge fluctuating? I can have a full tank of gas and the gauge will stay at the full level for a while then dip down to the half mark. A minute or so later, it creeps up to 3/4 then goes back to full after a while. Kind of irritating.

 

sounds like your float is sticking...i have never looked into it but i am sure you can remove it clean off some varnish and crud build up, re-install and be on your way. look at the factory repair books and see if you can find out more info on the gas tank.

 

mines been doing that for years, comes in spurts and usually lasts a tank or two before it magically goes away.

 

Yup, mine does it randomly but more like if i fill up my tank, the needle only goes up to 3/4 a tank, the next day once i start the truck, the needle will go to a full tank.

 

mine does that when im driving kind of except it sticks. it says im at almost half then i come back and its at a quarter

 

Mine did the same thing for years. Now it doesn't do it. My guess is when I was younger I wasn't driving more than 30 miles a week, now I am driving 200 miles a week and it probably just freed itself up.

 

Looking at the electrical it looks a pretty simple system. I don't see any sort of external module at the comb meter on the schematic (used to those going out on classic Minis). Power issues at the comb meter prob not as it looks like the same power circuit at the meter also connects to the cruise control and you did not mention issues with that as well.
Other than that, looks like you have three wires running to the sender. yellow/black, grey and brown. The brown is a ground for the system. Could be worth checking the ground is good and clean and tight. Says is located cowl/jb no.1 lower finish panel. May as well have a look at the wires going back to the sender as well just to be sure there is not a short type issue. Should be simple enough to follow them along.


Worth at least looking at as does not cost anything to check it out. Other than that I'd have to feel, as listed by many above, that probably an issue with the sender in the tank. Gummed up, worn, float issue sticking etc. Guess you could always throw in some Chevron fuel system cleaner and see if that frees it up. With my ultimate cheapness though, I'd be looking at checking everything out before spending anything.

 

It is actually pretty hard to get a float to stick in these things (though not unheard of so don't flame me here! lol) What IS very common is the sending unit itself. The sending unit is a variable resistor that's resistance changes as the float arm travels up and down the "card". It is very common for the sending units to develop varnish on the contacts (note to those who tend to drive around on less than a half tank of gas all the time) when the fuel level dips below the "card" location, and the card is exposed to air. This varnish can build up over time, granted we are talking a LONG time, not in just a few days. As this varnish builds, the contacts that run across the card do tend to clean the contacts on the card, but it is not a perfect world. This means sometimes the signal is incorrect. Also note that in these systems, it usually takes a longer time for the gauge to drop off of full than it does to change from say 3/4 tank to a half tank. This is due to tank design, as well as the arc that the float takes as fuel level changes. If all of the grounds that were mentioned test good, you should consider replacing the sensor. The sensor itself is not prohibitively expensive, and If you have already taken the time to remove it for inspection, you may as well replace it.

 

i thought i was going crazy watching my needle decide how much gas i have lol... it always seems to start acting up when i go up to tahoe... maybe the altitude? go figure...but it will stay on empty when its full