Problem with second tank...

I just bought a 87 R10 with dual tanks...I have never had this problem before so maybe you pros can help....first off it looks like a brand new switch for tank selection. But it doesn't act like it is running out of gas as I would expect switching to the right tank, it instead kills the motor instantly...like it may be grounding out something instead ...switch it back (while driving) and it fires back up on it's own instantly...is this common behavior for a switch problem? I don't know if it switches fuel pumps or just a valve? Like I said not familiar with it at all. Just wanted a few ideas what to look for as I trouble shoot. Thanks in advance!

im not sure if your style truck works in the same way but im pretty sure the newer trucks work like this.... two tanks with a fuel line that connects them both. fuel pump in tank 1 pumps fuel to motor. when that tank is empty, you flip the switch and the pump in tank 2 will turn on and pump fuel INTO tank 1 which then gets pumped up to the motor. durring this time i think pump 1 stays on the whole time... what you need to do is get a set of wiring diagrams for your fuel circuit and a meter and start testing things out.

you didnt mention if this new truck has an LS swap in it or not... if so, these motors need the 58psi at the rails constantly or it will die pretty fast. i shorted my fuel pump wire on my exhaust manifold once which obviously stopped the pump. motor died instantly. good luck

Still stock motor for now. Thanks, just found a diagram and going to check it out my next day off.