Fuel Guage Problem

[timheis]

My fuel gauge shows empty. The tank is nearly full. I took out the sender and measured a fluctuation of approx 26 O to 260 O. After reinstallation it measures
40 O. At the gauge it is also 40 O to ground. The voltage at the Gauge to ground is Source = 12V, From Sender = 7V. Thats 5V across the gauge with no deflection. When I short the sender out, I get full (buried) deflection. My question is, can a gauge lose it's sensitivity to lower resistances? Before I ordered a new one, I just wondered if anyone had a problem like this. BTW, the gauge is 20 years old.

Thanks
Tim

 

[Silvertip]

Re: Fuel Guage Problem

The resistance reading at the sender indicates the sender is ok. However, the float at the end of the sender arm may be saturated with fuel providing the incorrect reading, or the float arm may simply need adjustment. Remove the sender and operate the float arm manually through its entire range. The gauge should track for empty (float arm down) to full (float arm up).

 

[timheis]

Re: Fuel Guage Problem

Thanks Silvertip

The cork float was heavy. I replaced it and it works now.

With the key on it works good. When I turn the key off it pegs to full. Is this normal? With no power, how does it deflect to full scale?

 

[Silvertip]

Re: Fuel Guage Problem

Make sure the +12V or "I" terminal does not have 12V on it with the key OFF. If it does, you have something wired wrong. It is not unusual for the gauge to float to any reading, but pegging at full is not normal.

 

[Boatist]

Re: Fuel Guage Problem

Another Problem I have see on many boats including mine is the guage it self goes to empty when you turn the key off and the guage sticks. When you turn the key back on the guage slowly moves up to indicate how much fuel you have but if it sticks internaly the force to move it up slowely is not enough to break the sticking problem. In most cases tapping the guage with the key on will break it loose when the tank if pretty full. When it's low then even taping it will not break it loose. Some guages you can open up and clean the stop posts and it will work normal.