Originally Posted by Big Denny
I have a 1998 Land Yact and the gas gage only works half way. It tells me I am empty and I can only get 40 or 42 gallons in the tank. What is the fix?
From a full tank, if you know your typical fuel mileage, you can use the trip odometer to estimate how much range you've got, ignoring the malfunctioning fuel gauge. Just reset the trip odometer to zero every time you fill up, and completely fill up every time you stop for fuel. I did this for a while with my old pickup truck until I could get the sending unit replaced. Use your worst estimated mileage, and allow about 100 miles of range as a buffer to prevent running completely out.
To replace the sending unit, you may have to drop the tank and remove the sending unit (which might be incorporated into the fuel pump as a single unit). Replacing the sending unit with a new one is probably the most reliable fix, versus trying to troubleshoot and repair the old one.
Best to do this when the tank is as empty as you can reasonably get it. Gasoline weighs a little over 6 pounds per gallon (so does diesel), so dropping and reinstalling the tank goes better with a nearly empty tank.
Also, while you've got the tank removed, completely clean it to remove any built-up sediment or chemical goop. By the way, you're likely to have goop in your tank if you've mixed ethanol fuel with non-ethanol fuel and then let it sit for a while. Seems that ethanol doesn't play well with the additives it's supposed to replace.
also, it makes a difference what type of material the tank is made from. Ethanol also doesn't like fiberglass (it acts as a solvent for the fiberglass resin), so if you've got a fiberglass tank, you might be looking at a complete tank replacement. For metal tanks, monel is best. For plastic tanks, ABS plastic.