Hi, i have a 87 6.9 diesel and i have dual tanks and i know alot of times the switcher gets messed up is there anyway to test the tank switcher without running the truck out of fuel?

 

You can switch tanks at any time...Not just when 1 tank is empty...

 

Not 100% sure how the fuel lines run. If the two tanks fuel lines connect but you could probly pull a line off the tank when it is running to tell which tank fuel is comeing from.

 

Why do that, when there's a switch marked Front/Rear that tells you that?

 

You could get a meter to test for continuity in the switch when you push front to rear, That would easier then runingh tank's empty

 

From the cab, turn on the key.
Switch tanks and watch the fuel gauge.
If the fuel gauge moves when selecting the other tank the fuel tank selector valve on the frame is working.
If the fuel gauge stays the same the motor is not running in the selector fuel valve.

 

Fuel gauge don't work

 

Gauge never worked since I owned it

 

What if the gauge goes past full and the truck dies?

 

Then you have no ground at the sender or pump.

 

Sounds like a grounding issue

 

thanks guys.