Fuel gauge indicates 1/4 tank when it's actually empty

[Man With A Gun]

I have the dual tank setup so I can let it go "dry" (actually there's only 18.5 gallons that can be added so there is a 1.5 reserve).

But this happens when the fuel gauge is showing around 1/4 tank.

Does this mean my sending unit is bad?

Bad ground or connection?

[Dead Parrot]

If the gauge reads 1/4 when fuel exhausted on both sides, probably bad gauge. If it goes to E on one side and 1/4 on the other, probably bad sender on 1/4 side.

My original gauge would read E with a few gallons in the tank. One side reached E with about 4 left, the other had about 2. When that gauge died, the replacement reads E with very little left in the tank.

When I run my 20 gallon tanks dry, I can often get 20~21 gallons in them.

[wilkin250r]

If the gauge functions (meaning a full tank shows full, and the gauge drops as the level drops), it means you've got some other resistance in the circuit.

As Dead Parrot suggests, what does the gauge read on the other tank? Does it work properly, or does the other tank show 1/4 tank at empty also?

Might be corroded wiring, might be a poor ground connection, heck it might be a poor connection ANYWHERE in that circuit adding a little more resistance than it should.