Gas gauge not working

[svdreamer]

The gas gauge in the main gas tank doesn't work. It does in the aux tank. Is there an easy fix to change the fuel sending unit or will it require dropping the tank to get to it?

[Papa Joe]

My fuel guage quit and I crawled under only to find the wire to the sensor was unplugged. I simply plugged it back in and voila I had a fuel guage. I hope yours is as simple a fix as mine was.

[450Donn]

If this is a Ford chassis I would suspect that the tank selector valve is bad. On Fords and probably others, all the wiring for the tank gages and pump power is routed through the selector valve.

[svdreamer]

Quote:

Originally Posted by Papa Joe My fuel guage quit and I crawled under only to find the wire to the sensor was unplugged. I simply plugged it back in and voila I had a fuel guage. I hope yours is as simple a fix as mine was.

Wow, you lucked out! I hope mine is as simple, I'll have to look tomorrow.

[svdreamer]

Quote:

Originally Posted by 450Donn If this is a Ford chassis I would suspect that the tank selector valve is bad. On Fords and probably others, all the wiring for the tank gages and pump power is routed through the selector valve.

It's a Dodge chassis. I was reading up on fuel sending units and it said on the older models, it was a sensor that was located on the top of the gas tank with a door in the floor behind the front seat in a car to access it. Since this is a RV not a car, I was wondering if there was an access to the sensing unit or if it would necessitate the dropping of the gas tank.

[leadman]

Does it use one dash gauge for both tanks with a switch to flip to the tank you want? If so you might want to check the wires in that area. IIRC Dodge used a resistor on the dash panel on the back side for awhile.
I would also check the wires near the tank first. Some Dodge tanks had the sending unit on the front side, some were on top. It might be possible to reach in on the top of the tank if there is enough clearance.
The sending unit is a reostat like a dash light dimmer switch. A wire is wound around a semi-circle piece and the other wire is attached to the float in the tank. The level of fuel in the tank determines where the second wire is on the coiled wire, which changes the resistance, which makes the gauge read different.
That said, it is possible for this sender to only not work over part of the scale so if you add or remove gas it might read again until it comes back to the same spot. If this is the case it might be something you could live with, especially since you have 2 tanks. If this is the problem then a new sender will have to be installed.

[Dave78Chief]

Sender is installed in the top of the tank. If it is a loose wire you might be able to see it though you also might have to be a contortionist. Most likely you will have to drop the tank to access the sending unit. This is not fuel injection so it is an old style setup. I believe Winnebago used a relay under the dash to switch gauge and tank selector valve functions. The sending unit is an old style Dodge/Ford unit that has a 10-80 ohm range. Check to see if you have 12VDC at the actual selector valve when in switch is AUX position. No voltage when switch in MAIN position. The valve is most likely mounted on the inboard side of the passenger side frame rail about the same location as the muffler (just aft of the transmission support brace). There is a metal heat shield added between it and the muffler.

Here is a link to a a add-on version of a tank select valve/switch setup. Winnebago used a variation of this. http://cdn.wildhorses4x4.com/downloa...%2011-8-07.pdf

Given that yours works for the AUX tank, the fuel gauge circuits (and instrument cluster bi-metal regulator) are ok.

Dave

[svdreamer]

Quote:

Originally Posted by Dave78Chief Sender is installed in the top of the tank. If it is a loose wire you might be able to see it though you also might have to be a contortionist. Most likely you will have to drop the tank to access the sending unit. This is not fuel injection so it is an old style setup. I believe Winnebago used a relay under the dash to switch gauge and tank selector valve functions. The sending unit is an old style Dodge/Ford unit that has a 10-80 ohm range. Check to see if you have 12VDC at the actual selector valve when in switch is AUX position. No voltage when switch in MAIN position. The valve is most likely mounted on the inboard side of the passenger side frame rail about the same location as the muffler (just aft of the transmission support brace). There is a metal heat shield added between it and the muffler. Here is a link to a a add-on version of a tank select valve/switch setup. Winnebago used a variation of this. http://cdn.wildhorses4x4.com/downloa...%2011-8-07.pdf Given that yours works for the AUX tank, the fuel gauge circuits (and instrument cluster bi-metal regulator) are ok. Dave

Thank you again for such great advice, Dave. Dang, I was hoping it would be an easy fix. While I can do mechanical fixes, wiring and electronics are totally beyond me. I don't know what a relay looks like or how to test for voltage. This may have to be an auto shop fix.

[svdreamer]

Quote:

Originally Posted by leadman Does it use one dash gauge for both tanks with a switch to flip to the tank you want? If so you might want to check the wires in that area. IIRC Dodge used a resistor on the dash panel on the back side for awhile. I would also check the wires near the tank first. Some Dodge tanks had the sending unit on the front side, some were on top. It might be possible to reach in on the top of the tank if there is enough clearance. The sending unit is a reostat like a dash light dimmer switch. A wire is wound around a semi-circle piece and the other wire is attached to the float in the tank. The level of fuel in the tank determines where the second wire is on the coiled wire, which changes the resistance, which makes the gauge read different. That said, it is possible for this sender to only not work over part of the scale so if you add or remove gas it might read again until it comes back to the same spot. If this is the case it might be something you could live with, especially since you have 2 tanks. If this is the problem then a new sender will have to be installed.

Yes, it uses a toggle switch on the dash. I get no reading at all and it's been all the way from full to near empty.