Tank select switch on dash

[jik]

How does this switch work? Filled both tanks with diesel. Left switch on left tank. Gage showed full. Drove truck around for a couple of days. Gage show empty. Moved switch to right tank. no change at fuel gage. Does the fuel come from tanks automatically or do I have a problem? Filled left tank today and still shows empty. Truck is a 1989 6.2l dually

[highpockets]

On my gasser 1983 P/U the toggle switch is momentary contact and must be pushed in firmly to select. The motor that moves the selector valves is only powered briefly, but the toggle selects the gauge circuit continuously. Bob

[ropinfool]

The gas valve is different than the diesel valve. The diesel valve actually has a motor to shift valve position, this is due to having return fuel coming back to the tank. I need to push and hold the button for a couple of seconds for the valve to actually shift. If I just push the button the indication will shift tanks but the tanks don't actually shift. If your full tank is reading empty and you are pushing the button then I would think you have an electrical problem. I can't remember when the gage reads empty, ground or short or open?? A good way to tell if your valve is working is turn the key to on, don't start the engine, open the door and push the button, you should hear the valve. Or have someone else push the button while you are under the truck. Good luck. John

[jik]

Thanks.
Bad switch.