Community Forums

rphcampers · 05-06-2015, 06:24 AM

The fuel gauge in my camper pegs past full. I've read that this could be a ground issue or perhaps a sending unit issue. Does anyone have wiring instructions for the sender or other ideas? Thanks

jacwjames · 05-06-2015, 07:04 AM

I see you have numerous posts for your rig, it must be new to you.

Anyway, the fuel gauge sending unit, if like mine is made by Centroid. There is a method to adjust if it is functional. Here is a copy of the procedure. My sending unit was accessible and I was able to clean off the top to find the adjusting screw. Good luck and let us know if you are successful in getting it calibrated.

DtBt · 05-06-2015, 03:24 PM

Beware that algae can "short" the centroid sensor causing your symptoms. Use biobor jf if you are not already. Dirt can accumulate on top of tank and cause your symptoms as well. Centroid has a troubleshooting guide to aid in isolating problem. The sensors do fail on a regular basis. It is almost never the gauge itself.

Vanwill · 05-09-2015, 09:35 PM

As DtBt said, the tank sensors fail routinely on coaches of your age. The failure mode is sometimes the electronics in the head of the tank sensor, but I think more often it is deposits inside the aluminum sensor tube. Many folks have tried cleaning the inside of the sensor tube with brake cleaner or other solvent and been successful. It did not work on mine, and I had to replace the sensor. About $95 from Centroid. If you send Centroid the exact height measurement of your current sensor, it
will come to you pre-calibrated and all you have to do is drop it in.

Carefully label your wires as you remove them. And be aware that on some coaches there is barely enough room to remove the long sensor.

Mike Canter · 05-10-2015, 07:21 AM

Rphcampers, fuel sending units usually go low resistance for the fuel gauge to read full or above full. So if the wire from the gauge to the tank is shorted out then the gauge reads full. If the wire is broken or loose then the gauge reads empty all the time. The big question is if it is the wire, the sending unit in the tank or the gauge. If you open up the fuel tank door on the passenger side then you should be able to easily get to the sending unit top on the top of the tank. Mark the terminals and take the wires off the unit and see if the gauge goes to empty. If it does then the sending unit is at fault. If it remains at full then it is the wire or the gauge is faulty.

Coma · 05-11-2015, 04:55 PM

When mine failed, it went to over full. They can get fouled with algae, a diode can fail or detect water contamination. All show over full. Talk to the Lady at Centroid, she can look up the exact unit have it made to order and shipped to you in about ten days.

djhinds · 05-12-2015, 08:13 AM

My gauge went to full and stayed. Thought I was getting GREAT mileage at first but to no avail. Did the troubleshooting tests from Joel and was told it was a diode failed and I needed to replace sending unit. Took pictures with IPhone to identify wire locations, removed it (very easy) and gave my exact model number to Centroid and they made me an EXACT replacement. It was already calibrated. I used a tape measure to see how much fuel was in the tank, it was 1" above half. When new unit was installed gauge read just over half... perfect....

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Good luck
Dave

Mike Canter · 05-12-2015, 08:32 AM

Thanks Dave, that is great info.

rphcampers · 05-17-2015, 06:53 AM

Thanks for all of the ideas. Monaco tech support said I could test my fuel system by shorting the send wire on the solenoid to the neutral wire. At this point, the gauge should sweep to empty (cycle the ignition after shorting the wire). If the gauge goes to empty, the sending unit is bad. Mine stayed pegged past full... gauge likely the problem. Next test, short the send wire on the back of the gauge to the ground. If the gauge goes to empty, the gauge is good and your wiring from the sending unit is bad. Unfortunately, my gauge stayed pegged past full. The short seemed effective because it made the fuel light come on, even though the gauge did not go to empty. To find the send wire on the back of the gauge, I used a cheap AutoZone tester that lights up and beeps on a hot terminal. The ground bolts are on the mounting bar for the gauge. The hot wire beeps really loud and the send wire beeps softer (less hot). The ignition must be on for these wires to be hot. So.... now that I know my gauge is bad, any idea if I can repair it or where to source a new one? Thanks!