Dual fuel tanks not switching

[Critchy]

I have dual ful tanks and the boat will not switch from one tank to the other. My fuel gauge is not working either. It has bean tempermental for a while. I checked all wire connecters on the fuel gauge, the switch used to switch the tanks and also followed the wires all the way to the sending units. All wires and connectors appear to be fine. The fuel lines coming off of both fuel tanks go into this aluminum looking unit. And then one line into the motor. I chased my wires from the sending units, from my fuel gauge, and from the switch that switches the tank and they all plug into this unit. Also last time I was out I ran out of fuel. I switched the fuel lines going into this unit from the one that was being used that ran empty. I took the one for the full tank and plugged it into the hook up that was being used. Once I did this the boat had fuel again and started working. Like it didn't switch which one it was drawing from. Does it sound like this unit is bad? This is what I'm thinking. Also does anybody know what this unit is called? Thanks I appreciate it.
Critchy

 

[Silvertip]

Re: Dual fuel tanks not switching

The unit in question is the fuel transfer valve. It is electric. When you flip the switch a solenoid switches from one tank to the other. Since the gauge is not working nor is the transfer valve, I suggest you check the +12 volt feed to the transfer switch. If the system doesn't have 12 volts, neither the gauge nor the valve can function. Looking at the wires is not a valid check. You need to follow the current.

 

[Critchy]

Re: Dual fuel tanks not switching

How do I check the 12 volt feed? Also what would be the cause of this and how would I fix it? Thanks.

 

[Silvertip]

Re: Dual fuel tanks not switching

You need a test light or a multi-tester commonly called a volt-ohm-milliamp meter. These meters are available at most Home Improvement stores (electrical dept) for 10 bucks to about 90 bucks. Of course you then need to know how to use it but it is simply set to the 20 volt scale. Red lead goes on the circuit you are testing and black on ground. If you have voltage = good. If not = not good. Work backwards.

Current needs a complete circuit from battery positive through a fuse or breaker, to a switch, out of the switch to the device it controls then back to ground. If a wire is broken or disconnected, fuse blown, breaker open, switch defective, or the device is defective the system won't work.

Here is a diagram of a basic electrical circuit. It does not reflect your fuel selector circuit but it gives you a pictorial of what a complete circuit looks like. Siimply replace the light with any other device.

Here is a picture of a multi-tester being used to measure the resistance of a fuel sending unit.