My fuel gauge seems to be stuck past the full mark. I have driven over 200 miles so it looks like it is not working. All the other gauges are functioning fine. Which end should I start looking over to find the problem. Should there be a voltage at the meter? and if so how much?
Thanks again Im not that great of a mechanic, But I know there are many pros on this site!
Wayne

I await answers to this. My Left [rear] tank works fine, but when I switch to Right the gauge is always pegged full. Maybe I can find the fix here.

Ground or sending unit are both likely culprits. See if you can locate the sender. Not always an easy task in any RV. Start by finding the fuel tank and what is above it.

Senders are always variable ground circuits. 12v to gauge and a resistor to ground. Placing a ground wire on the back of the gauge will either read full or,empty. If either changes then the sender is culprit. If nothing changes suspect the gauge.

If the tank was completely full, it's not unusual for it not to come off the peg for over 200 miles.

OTOH, the sender or a wire or a connection could be bad.

The mid 80's P3somethings have electric pumps in the tank, with the sender alongside. There is a 3 wire connection to the tank: 12V to the pump, common ground, and sender wire. There is also a separate ground from tank to chassis. Yours is probably similar.

If the common ground gets flaky, the voltage floats and the gauge goes nuts. If you can get to it, check the connector at the top of the tank. (While there check the fuel lines lest they smite thee later.)

Some problems are due to poor connections inside the tank, removing tank is only option then.

quote:

Originally posted by Danny Z:
I await answers to this. My Left [rear] tank works fine, but when I switch to Right the gauge is always pegged full. Maybe I can find the fix here.

Danny, if yours has the GM fuel gauge, a dead short to ground (0 ohms)should read empty, and a resistance of 90 ohms or more (even an open) should read full. Anything between 0 ohms and 90 ohms will read somewhere between empty and full.

If you have an aftermarket fuel gauge, there are other values, and it helps to know the manufacturer, or at least the country of origin. Or USA, Europe or Asia.

So, you could have a selector switch that is not making contact with the sender wire, an open wire between the selector and the sender, a bad sender, or a bad connection at the sender or a bad ground back there. On mine, I found a corroded connection inside the sender. There is a post and a photo here somewhere. I fixed it for a nickel, and the price of a new gasket.

Can you get your hands on the connection on the sender? If so, ground the center connecter. The gauge should go to empty. If it doesn't, check for an open between that point and the selector switch. If it does, provide a good ground for the sender. Mine now has a wire fro one of the sender screws to the frame.

If no help, drop the tank and check the sender.

But, first, clean all the connections.

I had a problem with my fuel gauge where it would occassionally go all the way to full and then later return to the accurate level. I contacted Spartan and the person I spoke with was extremely helpful. They sent me two documents showing the various fuel tanks installed on their chassis. If you have a Spartan chassis I can forward these documents to you. You may need to contact Spartan to find out which one is on your particular coach.

There are three contacts on my gauge. Two of the conductors go to the sensor, a ground and a 12VDC supply to the sensor. The third contact is for 12VDC input. I have isolated my problem to the contacts on the sensor. I have cleaned the contacts and replaced the two connectors. When I take my next trip later this month I will be able to tell if it fixed the problem or not. I will keep this forum posted.

The terminals on the sender of our tank are quite close together. A couple of years ago I nudged one and my apparent fuel economy was elevated to fantastic. It did however return to normal when the wires were separated and taped.

Bud

But, OTOH, just think what great fuel mileage you're getting