Fuel gauge don't work... HELP

[06pwrstrokerbullitt]

Well every since I have owned my truck the fuel gauge has not worked, the truck is the 06 6.0 in my sig. Now that summer is coming up I will be taking it on some trips and really need to get this fixed, whatching my trip meter I have to stop quite often on trips to make sure I don't run low on diesel. Right now I have tried a new sending unit and that did not fix it. The fuel gauge is throwing a check engine light, so that tells me I don't think it is the gauge. The gauge will come up to the Empty mark when you turn the key on then falls back down to the bottom of the gauge. This truck has had an auxilary fuel tank in it before I bought it so I am not sure if that has anything to do with it or not. Any help would be appreciated.

[ruger#1]

So this truck had two tanks, Then there must be a switch to change tanks and the fuel gauge operation from one tank to the other.

[bigcountrysg]

It is a ground problem. The wiring problem will most likely be found back by the tank. Most likely the previous owner had a second gauge used for the auxilary tank. Most likely he spliced into the wiring for the sending unit in the original tank.

Drop the tank so you have access to the wiring. Check out the wiring and go from there.

[06pwrstrokerbullitt]

Originally Posted by ruger#1

So this truck had two tanks, Then there must be a switch to change tanks and the fuel gauge operation from one tank to the other.

It does still have a switch for the main tank and the auxilary tank but flipping the switch does nothing for my gauge.

[06pwrstrokerbullitt]

Originally Posted by bigcountrysg

It is a ground problem. The wiring problem will most likely be found back by the tank. Most likely the previous owner had a second gauge used for the auxilary tank. Most likely he spliced into the wiring for the sending unit in the original tank.

Drop the tank so you have access to the wiring. Check out the wiring and go from there.

I did drop the tank once but I was in a hurry and wasn't looking for wiring at that time so I will try that again and see if I see anything.