Fuel Gauge Registers Full All The Time

[Keith Duner]

Coach is a 2005 Monterey 36 w/3 slides.  Our trip to Yellowstone NP last week (from Denver) has resulted in a fuel gauge problem.  After filling up with diesel at a truck stop (high speed pump), I significantly over filled the tank from the drivers side, perhaps as much as one or two gallons spilled.  Ever since then, my fuel gauge has registered FULL, regardless of actual level.  Today I see that it has dropped to maybe 7/8ths on the gauge but actual is less than half a tank.
QUESTION:  Did the use of the high speed pump damage the internal fuel level components (not sure what those are) OR did the overfill wet down the fuel pump sending unit, causing it to see ground and therefore register FULL .  If this is a possibility, does anyone know where the external sender is located?  Thanks in advance for any suggestions.

[Keith Duner]

Answered part of my own question.  Sender is driver side. accessible if you cut the wheels hard left (and loose a few pounds).  Removed the three wires, cleaned them, the studs, and the face of the sending unit.  Still shows 7/8s full.

[Roy C Tyler]

I use CFN stations or Pacific Pride fueling stations.  They all have the high speed pump for the big rigs.  I have to just barely squeeze the handle to fill mine and I fill it right to the top.  It takes mine about 100 miles before the needle starts to drop on my gauge.  I doubt that filling it with a high speed pump damaged anything.  The overfill may have.

[Gerald Farris]

Keith,
You tank unit was not damaged by the high speed pump or spilling a couple of gallons of fuel.

To properly test your fuel gauge system, you need an adjustable rheostat, and the ohms chart for the tank unit. But you can make a few checks that will usually help in narrowing down the problem. First, determine which wire the dash gauge is using to feed current to the tank unit and disconnect it, the dash gauge should read past full. Next, ground it to the frame, the dash gauge should read empty. If the dash gauge passes both test, it is most likely serviceable, and the tank unit is defective if the tank unit has a good ground.  

Gerald  

[Keith Duner]

Thanks Roy, that's about the same with my coach, 100 miles before gauge starts to drop. Gerald, thank you for the guidance, I'll start the testing next.  I did contacted Beede web support (mfg of the gauge heads) but they did not make the sending unit.  Beede kindly pointed me to Centroid in Fla.  I found a tech sheet for sender adjustment on the web at http://www.centroidproducts.com/moncal.htm but have not talked to them yet. I'm a fan of KISS so I'll keep working on the obvious and easy solutions first.  And the beat goes on....

[David T. Richelderfer]

After filling my diesel tank the fuel gauge is slow, as well, to move down.  But, boy howdy, when it finally gets moving it seems to speed its way to 1/2 full pretty fast.  I can get about 825 miles on a full tank, but never go past 500; rarely do I go past 400.