Any thoughts on reviving a half-lazy tank selector valve?

[BDCarrillo]

Any luck with a straight 12v shot? Barring any mechanical oddities it does seem more like an electrical control issue. If it had crapped out mechanically I would expect it not to switch at all, or exhibit the same behavior on either switching event.

I've had similar issues with Ford door locks and traced it to an internal switch fault. One way was good, press the button to reverse polarity and it was very weak to ground.

 

[madpogue]

Just tried it direct, using a jump box. It flipped to rear, then to front, rear, front, about five times. Then it flipped to rear, but wouldn't flip back to front until I rapped on it with a hammer again. It'll flip to front on its own about 25% of the time. Rest of the time, it'll flip, but it takes just a slight rap. So I don't think it's the switch.

 

[BDCarrillo]

Well now you know 100% its an internal FSV fault. Last chance for it may be to look up the disassembly/cleaning thread.

 

[madpogue]

Last chance for it may be to look up the disassembly/cleaning thread.

I might do that after installing a replacement, so I'll have a backup. Meanwhile I can live with single-tank op, or the light-rap approach in a pinch.

 

[Black dawg]

I had one that I had to tap on to get it to switch to one tank, it was like this for the first month I owned it, and then never had a single issue with it again.

 

[OLDBULL8]

FSV tear down. Drill out the 4 rivets, just the crimped part, punch out the rivet's. The pic with the screw is what I used to go back together, just drill out one half for screws to pass thru. Added the filters on the suction side. When apart, you'll see how the slide switching operates.