Save me some searching please!
TIA,
Vince

 

Most likely the float has sunk. Contrary to the listings you might find, the float can be replaced separately; it just snaps onto the arm. Unfortunately I don't know of a good quality replacement. I replaced mine about a year ago, IIRC it was from Summit Racing. It appears to have sprung a leak and sunk already.

One slim possibility is that the sending unit has hit a bad spot on the variable resistor. But it's unlikely. Typically when that happens, it fails as an OPEN circuit (infinite resistance), which would appear on the gauge as pegged way past full. For it to be the sending unit, it would have to fail as a SHORT circuit (zero or very low resistance).

 

Thanks man! Ill run it on the front tank and see if it goes down.

 

Hmm, that's confusing. Isn't the gauge reading on empty on the front tank now?

 

Its possible that the selector valve down on the frame rail is stuck on the rear tank.

 

^^^^ +1; important question - does the gauge reading change when you switch tanks?

 

Yup, it switches.

 

And the gauge always reads empty when you're switched to the front tank?

 

Yes. The gauge was a bit wonky at last fill up too. It read lower than what I thought was in the tank.

 

So it reads too low when it's full, and empty when it's partway full? Classic float failure; it's partway filled with fuel. The teeniest tiniest pinhole will do it. Last one I pulled, I couldn't actually find the hole. No matter which way I oriented the float, I couldn't get fuel to just drain out of it. But there was fuel in it no doubt. It would only come out when I shook it.