I filled up my 94 u280 right before leaving for PA and the gauge read above full like normal. After driving 450 miles through hills and running the generator the gauge hadn't moved. I put in 73 gallons to get home and the gauge still hasn't moved. In the past the gauge has been slow to move off full and erratic at half so this is new behavior. I have read the centroid site and it states that water content in fuel will cause this but before I go and tear a strip off the fuel station has anyone ever had a sender fail to the full side? I do add lucas fuel stabilizer with the fuel as per the injection repair shop that has rebuilt a few pumps and injectors for me on other jobs. Am I correct that if I remove the sender and hook it up again it should immediately read empty to diagnose?
Would think if the gauge goes to "E" when you turn the key off that would eliminate the gauge. Not sure what sender you might have in the tank. I think mine is just a mechanical float type with an electrical connection. It looks like I could remove it without moving the tank. I haven't had a problem, but it does take about 100+ miles before moving off full with a full tank.
It used to take about that long to come off full but this was over 940 miles. Further diag to follow whether the sender has shorted or the fuel has water. Centroid uses resistors and water causes a full reading because it is more conductive than fuel
Ok, I just googled "centroid fuel sender", and I see that I was wrong about what I have on my coach. Found a link on Barry's website.
Centroid Fuel Sender Calibration (http://beamalarm.com/Documents/Centroid_fuel_sender_calibration.html) Let us know if you find the problem.
Working on it. So far I used my jiggle siphon to draw some fuel from the very bottom of the tank into a gallon jug last night. Will see if any water settles to the bottom. It is possible the Lucas is conductive enough in the concentration in the tank to be the issue. Will have to pull the sender to see what it reads out of the tank.
Unplug the sending unit turn key on is gage at e or full? If it is full your wire from gage to sending unit is grounded. If it is at e ground wire to sendinh unit gage should show full. This will verify gage is working and problem then would be with sending unit.