Fuel Gauge stuck on full

Referring back to a post I made in Sept 2001 wrote:
The fuel sending unit is a variable resistor controlled by the action of a float arm. When the fuel level is low, resistance in the unit is low (Empty = 17 ± 2 ohms). When the fuel level is high, the resistance is high (156 ± 4 ohms).

Wire number 1203 (BK/LB) is connected through connector C441 (Left rear of vehicle) and C1046 (Inside left frame rail, near 4WABS module) to G204 Ground (Lower left corner of support [fire] wall. Wire 29 (YE/WH) is the signal going through connector C441 (Left rear of vehicle), C1046 (Inside left frame rail, near 4WABS module), C141 (Lower left corner or dash) and C205 (Left of steering column, behind I/P) to the Instrument Cluster.

At the time, I had a 2001 Residency. The gas gauge quit working soon after I bought it. I had to by pass the wires to the sending unit when I figured out there was no connectivity between the dash and the tank.

After I dropped the tank and check the ohm readings on the sending unit, put it back in and raised the tank back up, the engine wouldn't run because the fuel pump wasn't pumping. I dropped the tank again and pulled out the pump. I found the Siamese 1/4 inch spade connector on the pump had lost its tension and burned up the connector. I cut the connector off the end of the wire and replaced it with individual 1/4 inch spade connectors. I put another 40,000 miles on it and the fuel pump was never an issue again.

Back to the sending unit. I traced the wires along the frame rail. There was a connector close to the tank. When I shorted it nothing happened. The gauge should have gone to empty but it stayed on full. I found another connector alongside the emergency brake. When I shorted the wires there, the tank went to empty. I knew then the wires lacked connectivity between that connector and one near the tank. I bypassed that wire and the gauge worked great afterwards. I never replaced the sending unit or the fuel pump during the 16 years I owned it.

When the gas line to the generator started sucking air later on I wasn't going to drop the tank again. I had a pass-through compartment above the gas tank so I cut a hole though it to expose the tank and sending unit/fuel pump flange where the generator gas line comes out. It was a tight squeeze to get at but it was a lot easier than dropping the tank again.

I saved these notes - they pertain to the wiring diagram I had for my 2000 vintage F53 chassis and helped me locate the wires to the tank:
Wire number 1203 (BK/LB) is connected through connector C441 (Left rear of vehicle) and C1046 (Inside left frame rail, near 4WABS module) to G204 Ground (Lower left corner of support [fire] wall. Wire 29 (YE/WH) is the signal going through connector C441 (Left rear of vehicle), C1046 (Inside left frame rail, near 4WABS module), C141 (Lower left corner or dash) and C205 (Left of steering column, behind I/P) to the Instrument Cluster.

Yep, can be pricey for fuel pump and sender IF you can find one, Motor Homes tend to make this even more of a challenge since tanks are often much different than say the pickup version..

However, many stepvans use the same chassis as motor homes so, perhaps you might be able to find a stepvan sender and fuel pump that will work..

A good source for stepvan parts is MILL SUPPLY INC

HERE is a link to their Stepvan fuel tanks, pumps and senders..

Just went through similar issue with fuel gauge.
Gdetraier option two may knock the float loose from what every is holding it.
In my case it would stick at about 1/2 tank. The float rides on a open resistor to change fuel level.
Hitting it did not work! after draining nearly all the fuel, I was able to see movement in the fuel gauge.
I decided to fix it correctly. Took to my heavy repair facility. Resistor was rubbed to the extent it snagged the arm. Tried to get exact replacement. Parts houses said this is the one, wrong my tank is 15 inches deep, replacement is 12 inches.
Had the shop modify the complete assembly that came out of tank. New float mechanism, and most important a new fuel pump.
Tank your heart medicine as in my case expensive! Trace over $1000.

If the rig has more than 60K miles on it, replace the fuel pump as well if the tank must be dropped. A floor transmission jack works best.

Sender float is sticking/stuck.

Typical and common issue with older vehicles which sit for long periods of time (I had a 2003 F250 that had a lot of miles on it and eventually had the same issue with the sender sticking when tank was low and you filled it full and the gauge didn't go up for many miles).

Options are:

1) Live with it.

2) Use a 2x6 cut to a ft or so long then use a 3 lb hammer to "tap" on the tank sides and bottom (hit the broad side of the board please).

3) DROP the tank to remove the fuel pump/float assy and REPLACE..

I would attempt #2 (kind of what I did and it seemed to work for a while), then if no joy, #3 would be the best way to fix correctly.

• Gauge is probably seeing too low of resistance between the gauge and tank float
• Sever that wire. Does the gauge now not rise?
• Use an Ohm meter between the severed wire side and chassis negative. How many ohms show on the meter?
• There are NO ALTERNATIVES tothis test
• Doesn't matter where the guage to tank wire is severed.

NEVER EVER EVER direct short this wire to ground