Trojan Boat Forum

My port side fuel tank guage appears to be nonfunctional. I filled the tank up so I know the tank is in fact full, however the guage is not reading or registering the fuel level. What needs to be replaced if the guage is not working? The guage itself and I assume there is some sort of mechanism inside the tank that might need to be replaced as well?

3 things to look at... it can be any of these
1) the wiring, is there continuity from gauge to tank sender
2) does the gauge function when Voltage is applied.
3) does the sender vary the voltage output to the gauge... need to measure this at low and full tank.

part of 2) does the gauge move when ignition is turned on and off?

You might find it is the wires and connections.
If you have a Voltmeter you can check the above items.

The sender could also be stuck and so not showing full tank.

Start at the gauge easiest to check... apply 12V across it's terminals does it move?
Do you have Voltage from sender wire to ground when ignition is on?

my bet since i had this problem once. check the wire connection at the tank sending unit.

If the connections at the gauge and the sending unit look good including ground wire, try this:

- remove the sender wire from the sender at the tank (typically center post)
- jump it to ground.
- turn the key to the "ON" position

If you get a full sweep at the gauge ("FULL") without any flickering, your wiring and your gauge are good and you should suspect the sender.

I don't know the type of gauge you have, there are typically a couple of different resistance types. If you are handy with a meter, you can check the sender as follows before taking it out:

- Turn ignition off
- On a 240 ohm gauge and sender combo for example, with the sender wire still off, you should have pretty close to 0 resistance on a full tank from the sender wire to ground. Infinate resistance means an open circuit in the sender. Close to 240 ohms would be the reading on an empty tank.

CORRECTION: the resistance reading is taken at the sender from the sender post to ground, with the sender wire off, not from the sender wire to ground.

Thanks!! Located this link as well.

http://www.downloadingfiles.co.uk/telef ... ystems.pdf