When I switch to the right tank the engine quits in about 10-20 seconds.

I've taken the line off at the tank and the fuel is gushing out so probly not the problem there.

Scott,

You didn’t specify what type fuel selector/fuel system you have, but in any case, I’d take it off and examine both the fuel inlet and return passages carefully. If the valve is turning past the “right tank” detent, it can block one or both ports. While you have it off, disconnect the line at the tank and blow it out. DON’T try to blow it out while it’s connected to the tank! Several bad  things can result.  Good luck.

Bob