Fuel gauge always reads low on 1991 Sea Ray 170

[OregonMTB]

Any thoughts or advice? When I fill it--it reads full. After a half day of boating it drops to 1/2 a tank. If I go to fill it up--it only takes 5 gallons. I have a 22 gallon tank according to my owner's manual. After a full day of boating (or two half days), it reads empty. If I go fill it up, it will only take 10 gallons.

Is the sender mounted inside of the tank?

 

[Lazy Daze]

The good thing is that this is a super simple system. The only "bad" thing could be access to the sender (mounted on top of the tank, with the float extending into the tank), but in most cases you can either access it from the engine compartment or through a removable deck plate in the floor. Sometimes, you'll remove the whole panel that is above the tank. Whichever way it is it really isn't that bad, at all.

First, double check your connections on the backside of the gauge - not just by looking. Remove, clean and reinstall.

If all looks good, then with the key ON, remove the pink wire from the sender and touch it to the ground at the sender. The gauge should swing to FULL. When you remove the pink wire from ground, the gauge should read EMPTY. This means the wiring from the sender to the gauge is good, along with the gauge. Replace sender and go boating. In 99% of the cases, a bad sender is the issue. The windings on the resistor get worn - along the metal wiper. You can try cleaning them, or forcing the wiper to make a better contact - but that is usually a short lived (if at all) fix.

 

[Mike Blake]

Here's where I got mine. http://moellermarine.com/contact-us/ Fuel sender that is....................

 

[OregonMTB]

Thanks! I will try that.

The good thing is that this is a super simple system. The only "bad" thing could be access to the sender (mounted on top of the tank, with the float extending into the tank), but in most cases you can either access it from the engine compartment or through a removable deck plate in the floor. Sometimes, you'll remove the whole panel that is above the tank. Whichever way it is it really isn't that bad, at all.

First, double check your connections on the backside of the gauge - not just by looking. Remove, clean and reinstall.

If all looks good, then with the key ON, remove the pink wire from the sender and touch it to the ground at the sender. The gauge should swing to FULL. When you remove the pink wire from ground, the gauge should read EMPTY. This means the wiring from the sender to the gauge is good, along with the gauge. Replace sender and go boating. In 99% of the cases, a bad sender is the issue. The windings on the resistor get worn - along the metal wiper. You can try cleaning them, or forcing the wiper to make a better contact - but that is usually a short lived (if at all) fix.