Fuel Gauge always full

[tjb22]

I have a 1999 268 Islander with a single OX66 250 for power. I have problem with the Yamaha gas gauge, it always reads full. It is a Royce Industries sending unit which I started playing with. http://www.royceind.com/flexi-sensor.php
I took the flexi-sensor unit out and as I am pulling it up the gas gauge starts reading lower so I'm thinking that the float in the tank is stuck at the top of the sender. Before I pull the unit is there anything I should check 1st? Royce has been helpful with their support but before I start cutting wires and removing the sender is there anything else I should check? Gauge was working fine before winter storage but not now.

Wish the fuel tank was always full!

 

[seasick]

I don't know why you would need to cut wires. The sender lead and the ground should be using connectors (sender) or a spade lug for the ground.
If as you remove the sender, the fuel level indication changes, I suspect the float is moving. So if it is but the gauge reads full when the unit is bolted in, the sender may be bad and is shorting the sender signal to ground when screwed down.
Disconnect the sender lead and the gauge should read empty. ground it and the gauge should read full. If both those tests work, sender is issue.

 

[tjb22]

Finally went back down to the marina, fuel gauge sender is hard wired so I will need to cut wires to check it. Pulled the whole sender unit to check the float and the float was fine, not stuck and the magnets where in place. When removing the tube flexi-sensor a 2nd time, no change on the fuel gauge so I'm thinking that the sender lead is grounding out somewhere. I'll be cutting wires this weekend to to test the sensor and I'll try grounding it to see what happens.

 

[seasick]

Finally went back down to the marina, fuel gauge sender is hard wired so I will need to cut wires to check it. Pulled the whole sender unit to check the float and the float was fine, not stuck and the magnets where in place. When removing the tube flexi-sensor a 2nd time, no change on the fuel gauge so I'm thinking that the sender lead is grounding out somewhere. I'll be cutting wires this weekend to to test the sensor and I'll try grounding it to see what happens.

You said then when you pulled out the sender the gauge started to read lower. If that is true, your problem is not a grounded sender lead at least in the wiring.

 

[grady23]

I had this problem too. I solved it by purchasing a WEMA made sender and haven't looked back. They are available online from: http://www.wemausa.com/tank_sensors/tan ... ensors.htm

I have no financial interest in the company -- I just think they make reliable equipment and it's resonably priced.

Be careful about screws they send -- Sometimes they are metric thread and can also be too long.
Give them a call if you have any questions!