Dual fuel tank trouble switching

[AdamS86]

Ok I know this topic has been covered extensively but I can seem to find my specific problem anywhere…
Alright,87 GMC R1500 TBI, Right tank works flawlessly. Switch to left tank(which is full), sputters and dies. Also gauge barely quivers but doesn’t move.
I’ve checked dash switch, good. Checked to make sure both pumps are working by using the bypass on the fuel pump relay, both pumps run.
I feel like this is something simple but I’ve been trying to figure this out for a few days now and I’m getting frustrated.

 

[AdamS86]

Ok I should’ve kept reading. Sounds like it just the selector valve…
And BTW, who at GM decided to hard line all the way to the valve, then transition to rubber for 1.5”?! Hopefully I don’t screw those up

 

[dvdswan]

Sounds like a switching valve. you should be able to apply 12v to power pin and here it click.

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https://www.gmsquarebody.com/threads/1973-1991-wiring-manuals.14498/

Just hope it's not the problem I had which was several. Bad switching valve, dirty tanks, clogged socks, and degraded feed lines.

 

[AdamS86]

It was the switching valve. Local parts shop had one, changed it out with minimal issues. Fixed all my problems lol