Diesel tank over fill

[IMP]

We have one that the return fills one tank only, until it runs out even with the cap on. It looks like it is coming from the other tank ?? the lines look like they are in the right place
any ideas ?

 

[W427]

@IMP - in my study of dual-tanks for other reasons, and in a general sense, dual-tank switching valves may fail or operate improperly for several reasons. Common among these are electrical switch/wiring, valve /solenoid failure or sticking, and incorrect connections. Online references to dual-tank diagnostics may help.

I don't have my Itvees here to look-at for reference, but I would begin by testing for proper control signals in the switch and wiring. If switching power to the valve is clean and strong at full voltage, I would test for engine-off signs of operation through feel and sound while a helper is switching.

If tests are good so far but no joy, I would safely connect fuel-proof tubing from the return ports to a container for bypass flow testing. This should confirm if the valve is routing through the correct ports (connection verification), and if the valve is operating properly without internal leakage or partially-diverted flow. This post describes what I might do. Take all necessary precautions for safety with fuel if you choose to do anything similar. Be safe and responsible!

 

[IMP]

@IMP - in my study of dual-tanks for other reasons, and in a general sense, dual-tank switching valves may fail or operate improperly for several reasons. Common among these are electrical switch/wiring, valve /solenoid failure or sticking, and incorrect connections. Online references to dual-tank diagnostics may help.

I don't have my Itvees here to look-at for reference, but I would begin by testing for proper control signals in the switch and wiring. If switching power to the valve is clean and strong at full voltage, I would test for engine-off signs of operation through feel and sound while a helper is switching.

If tests are good so far but no joy, I would safely connect fuel-proof tubing from the return ports to a container for bypass flow testing. This should confirm if the valve is routing through the correct ports (connection verification), and if the valve is operating properly without internal leakage or partially-diverted flow. This post describes what I might do. Take all necessary precautions for safety with fuel if you choose to do anything similar. Be safe and responsible!

Thank You We will try that
Alex