Fuel Gauge Reading Inaccurate

[tahoejag]

Gauge still reads full after running boat hard for a few days. Did some testing on gauge and sending unit:
​- Unhooked both wires from sending unit, ohm meter on sending unit 50 ohms.
​- Connected sending unit wire to ground wire at the tank - fuel gauge showed "full"
- Volt meter on fuel gauge - 11.5 volts.
​- Continuity test from earth ground to sending unit wire on gauge - OK.
​- Continuity test from earth ground to ignition wire on gauge - OK.

​It appears that the gauge is operable and I am getting resistance reading from the sending unit. Possibly the sending unit is "hung up"? I doubt that I am getting that good of fuel economy considering how the boat was ran recently.....however I did install a new prop for efficiency. Any other suggestions or things to check are invited. Thanks!

 

[Scott Danforth]

clean all the connections.

your sender and gauge are 33-240 ohm units. corrosion on the signal wire will skew the gauge

 

[tahoejag]

clean all the connections.

your sender and gauge are 33-240 ohm units. corrosion on the signal wire will skew the gauge

​So if my reading is 50 ohms at the sending unit, that would be almost a full tank...yes? I have cleaned all connections, and will run it some more and see if the gauge does come down. Thanks!

 

[Scott Danforth]

could be your float arm is not adjusted correctly. if that is the case, your going to have to pull the sender and look

 

[Silvertip]

Fuel gauges depend on the sending unit arm position for a reading. Since this is a "float" system, attitude of the boat, in the water or out, running on plane or not can all affect how the gauge reads since the attitude of the tank affects the reading. If the float is not hanging up, you can adjust the arm to give you an accurate reading when full, empty or even 1/2 tank but only one of the three. Adjust the float for an accurate empty reading. You then know when it's time for fuel. You already know when the tank is full because you filled it.

 

[JoLin]

In line with what Silvertip said, the only time my gauge is pretty accurate is when the boat is at rest or traveling at idle speed. My tank runs front-back and the sending unit is near the back of the tank. My gauge always reads high when the bow is up.

My .02

 

[tahoejag]

In contrast to your gauge, mine must be toward the front for when the bow is up the gauge will read less. It takes some time to come off full when topped off with fuel. Just may be the case here. I am going to run it more and see what happens. Will update later with the findings.

 

[tahoejag]

After all said and done with cleaning connections and meter testing....Ran boat today for a while with rough seas. Gauge did start to come down off of full reading. Boat must be getting way better fuel economy with new prop and gimbal bearing recently changed. (old gimbal bearing was froze solid yet no sign of water intrusion...mechanic said "hmmmm, odd") Thanks for every one's advise and guidance!