fuel sending unit

[letsgo]

I have a 2003 H.R. Imperial, trying to locate the fuel tank sending unit, my fuel guage reads above full does not move, owners manual says it could be an indication that there is water in the fuel tank , I found what appears to be a drain hole or plug, in the bottom of the tank it looks like a allen head, has alot of undercoating around it anybody have any experience in removing this ? So my question is two part location of sending unit,and any one ever remove the allen bolt i assume it is a drain hole?

[walt2137]

The fuel sender is a Centroid sender and should be on the passenger top side, Your problem could also be a bad ground try running a new ground wire to the unit. I also attached the test instructions for the sender.

[Diplomat Don]

letsgo.....My sending unit is on the driver's side, top of the fuel tank. I'm not familiar with your coach, but here's where mine is located. You should have two fuel filler doors on both sides that are built into larger bay doors that are not designed to open with a latch. On the bottom of that driver's side door is a couple of screws that keep it from opening. Again, if its like mine, if you open this bay door you'll have access to the top of the fuel tank and the sending unit.

Most of the sending units were built by Centroid. Here is a link I posted a couple of years ago about adjusting the gauge. http://www.centroidproducts.com/moncal.htm

I was told by Centroid that if there is water in the tank the gauge can build algae on the tube and not work properly.

I would not trust removing that allen bolt from the bottom of the tank. People occasionally have leaks at the weld/plug that the allen bolt screws into. I would be afraid of cracking that weld trying to remove the allen. If necessary, I would drain the tank by siphoning it out.

[nplenzick]

There's no need to drain the tank to remove the sending unit.
I can attest to water ruining these units. When I had a problem with water in the fuel tank the other year, shortly there after my sending unit went bad. Had to replace it with a new one.

[DtBt]

When my centroid failed I removed it and found a small bit of algae had worked its way up into the tube. I would say remove and inspect before replacing. I now use a good algaecide to prevent algae forming if I sit for an extended period. I finally replaced the centroid fuel sender(16566) with a VDO 226008, 0 to 90 ohm old fashioned float type sender. I have never been satisfied with the centroid operation with it calibration issues and wild swings of the gauge. The VDO sender is rock steady so far. The only minor point is that at full the needle is barely at the full mark and you loose the low fuel warning. Installation is a bit tricky. Baffles should be located to insure no interference with the float. Due to the low clearance on top of my tank, the top length adjustment should be marked then disassembled. Insert the bottom section into tank partway and reassemble.