Fuel sender unit for aux tank

[Stesh]

Hello new to forum need some help. I have a 2001 222 fisherman. The aux tank fuel quantity is showing one bar and flashing. I can not put any more fuel in it is full( or I think it is). I think the sender might be bad. Is there a separate sender unit for it and where is it located? Thanks in advance

 

[SkunkBoat]

The most common cause of that is that the tank ground wire is off. Check at the top of the tank and check for green wires connected to the neg battery terminal.

Also, there is probably a switch on the dash that changes the gauge to read Main or Aux. There could be a connection problem there.

Also, not sure if you are new to the boat...the gauge will take a minute to readout after switching

 

[Stesh]

Thanks Skunkboat. Is it only one sender unit or is there a seperate one for the aux. I will check the wires tomorrow. i know it takes a minute for proper reading. The main reads fine, when i switch to Aux it goes down to one flashing bar. Is the green wire connected to both batts or just to one? Thanks again.

 

[Lite Tackle]

Thanks Skunkboat. Is it only one sender unit or is there a seperate one for the aux. I will check the wires tomorrow. i know it takes a minute for proper reading. The main reads fine, when i switch to Aux it goes down to one flashing bar. Is the green wire connected to both batts or just to one? Thanks again.

Separate senders for each tank. Should be able to pop deckplate to inspect and check voltages. Switch should be an on-on and routes sender current to gauge.

 

[Stesh]

Thanks Lite Tackle. Found the one fr the main but unable to find the one for the Aux. Any suggestions?

 

[seasick]

You don't check voltages for a fuel sender. It is a variable resistance device, we called them rheostats in older days.
There will be an access plate on the deck or some other way to access the sender. The sender is usually near where the fuel pickup is connected.
I assume your green wire is the ground. Both senders have a connection to a ground which is usually a connector on the fuel tank if metal. The tank itself must also be grounded. That connection will run to a ground buss somewhere and that does not have to a physical connection at a battery. There is a thickish cable at a battery that is smaller size than the heavy one that connects to the motor. The smaller one runs to a common terminal connection and that most likely will be under the helm.

For a simple test, locate the aux sender wire that connects the sender to the tank selection switch. It may be pink. Unplug it from the tab on the sender and connect it using a piece of wire to a good ground. You can try the ground connection on the sender/tank. If the gauge now reads the correct level, your sender is probably bad.
If it still doesn't work, connect the sender pink wire to a known good ground using a piece of wire that will reach the battery negative terminal (either battery if you have two)
If the gauge reads correctly, your tank ground is bad.
If both those test fail, you need to find where the wire from the sender connects to the tank selector switch. That should have three connections, one common that feeds the gauge (that works since the main tank reads levels)
The other two connection are the feeds from each tank. Jump each one to a ground and see what the gauge does. If it reads full for each terminal, the wire for aux tank is bad.

The switches don't go bad often so in all likelyhood, you have a bad sender or a bad tank ground

 

[Sparkdog118]

Do you have deck plates behind the driver seat on the floor? Or in the console?

 

[dogdoc]

I may be wrong here but if you jump the sender wire to the sender ground shouldn't the gauge read full ( 0 resistance). If you jump the ground to neg buss in battery compartment if ground was bad should now read accurate level. Intermittent bad ground was the issue on my boat and so now i verify using a long jumper wire once in awhile if I see gauge at helm wonky

 

[seasick]

I don't see where I said the opposite but I may have.Grounding the sender wire either alone or still connected to the sender should make the gauge read full.
Grounding the ground connector at the tank should have no effect normally but it the gauge reads correctly when you do, the ground is bad

 

[Stesh]

Thanks for all the info guys found it in center console behind some panels need new sender unit.