Fuel gauge, sending unit problem

[CJY]

It does not work. I own an 89 cajun fish and ski with a 70 hp johnson. It is, and has been stuck on full for the entire time I have owned it. I removed the component from the tank to make sure it was not frozen into the full position. It was not. I made sure all my connections were good to the tank, battery and gauge. All was ok.

The part that goes down into the tank to measure fuel amounts (sending unit?), is the type that has a float on one end with a hinge in the middle which allows it to bend up or down depending on the fuel level.

Is there a way to test individual components such as the gauge or the sending unit to help identify my problem?

I don't know what else I should do. Any help or suggestions would be appreciated.

 

[DJ]

Re: Fuel gauge, sending unit problem

If the pegged on "FULL" I suspect a short, or a mis-wire.

Easy to check.

1. Identify the "hot" wire and the ground wire on the fuel sender-at tank. The "hot wire will usually be red and will lead to a a harness.

2. With the key "on-NOT START" gound the hot wire.

If no movement, STILL ON FULL, check the ground wire. It should be grounded to the battery-NOWHERE ELSE.

3. IF still stuck on full, remove the guage and bench test.

To bench test:

1. The guage should have three wires.

a. ground
b.12v.
c. light

The light (ilumination) wire will be obvious.

While on the bench, hook 12volts to either terminal, you should see a guage swing. If not-reverse.

If the guiage does not swing, defective guage.

If it does, you have a wiring issue between.

I would suspect a ground issue with the dashboard lighting circuit. Boatbuilders tend to put too many grounds, on that one ground circuit.

Unfortuneately, boatbuilders also tend to wire things to read "positive" should there be an electrical issue.

 

[Gary H NC]

Re: Fuel gauge, sending unit problem

I have tested the sending unit with an OHM meter.Move the arm up and down to see if the ohm reading changes..no change-bad sender...But i bet Djohns advice may be correct also..