Backward Fuel Gauge

[mattpresley]

Since the day I thought I bought this truck with a full tank of gas only to run out like 70 miles later, my fuel gauge has been fully operational but backward. When I fill up to a full tank the needle is on E and the gas light is on. it than works its way to F as I drive around. This is such an odd and unusual issue I havn't been able to find any material on it and don't even know where to begin. Has anyone else here experienced this issue?

 

[adsm08]

Dude, that shouldn't even be possible. It's a pretty simple circuit, power in, variable resistor on the ground, and as fuel goes down resistance goes up, needle goes down.

The only thing I can think of, and it's way out in left field, is the wrong level sender. Some of the older ones operated backwards from the newer ones. Resistance went down as the fuel level dropped. If someone, somehow, put one of those in it. Not likely, but it would explain the backwards operation.

 

[mattpresley]

Dude, that shouldn't even be possible. It's a pretty simple circuit, power in, variable resistor on the ground, and as fuel goes down resistance goes up, needle goes down.

The only thing I can think of, and it's way out in left field, is the wrong level sender. Some of the older ones operated backwards from the newer ones. Resistance went down as the fuel level dropped. If someone, somehow, put one of those in it. Not likely, but it would explain the backwards operation.

Hahahaha even adsm saying is shouldn't be possible. Thats just my luck. Guess if the only practical solution you can think of is the level sender than, I guess I will live with my backward gauge and fix this if/when the fuel pump goes. I just gotta remember to pull the gas light bulb (drives me nuts) when I get in there to pull the tpms bulb.

 

[mattpresley]

This truck was a fleet truck. The dealer I bought it from specialized in retired fleet trucks. God knows what kinda in house repair caused this haha

 

[adsm08]

Now, does the TMPS light flash first, or does it just stay on solid? As annoying as those systems are to work on they are kinda handy. They get even nicer if you pony up the $30 for the reset tool.

 

[mattpresley]

Now, does the TMPS light flash first, or does it just stay on solid? As annoying as those systems are to work on they are kinda handy. They get even nicer if you pony up the $30 for the reset tool.[/]

The system worked just fine until I replaced the rims.. now I don't have any sensors. Screw it I got by just fine without tpms for a long time.

 

[RonD]

Yes, that IS an odd one.

Since it works....but in reverse the only thing I could think of is that either the sender or the gauge was swapped.........but sender or gauge would have to be from a pre-'86 Ford, that is when they switch to the current system.

Not that it would be worth it but you could build the circuit that would reverse the OHMs, and install it on the sender wire.