Well, I did the fuel tank selector valve. First, I would recommend spending a few extra bucks to get the Ford unit. The ones from NAPA work great, but the electronic connector doesn't interchange. You'd need the adapter, that is special order adn will set you back some extra time. What is happening? Is it not switching tanks? Leaking? Sucking from both tanks? If it is the later two, then you probably have a bad selector valve. If it is not switching tanks, I advise you to get your voltmeter, find which pins have voltage, then with teh key on, flip the switch....the voltage should reverse polarity. That is in one position, you should have +voltage, and when you flip the switch it should be -voltage. Really all the selector switch is is a double pole six connection switch. Travis helped me to understand mine and he's the best authority here on this sort of thing, but I digress, my problems were 1) selector valve sucking from both...2) no switchover from an electric problem. The switch is pretty durable, so you pretty mucha are looking at the valve or the wiring for your problems. I wound up rewiring the whole think and putting in a redneck type system. Its temepermental, but usually gets the job done.
Maybe tow cat or beretz will chime in. I know they both did this already. Seems I remember a few more too.
