Cripes, it's just so easy to use an electric switching valve with a "double pull-double throw" switch that switches tanks AND sending units at the same time. This is especially important when using an electric fuel pump because electric pumps are pushers, not suckers. If you have a manual switching valve placed somewhere within the drivers reach, the electric fuel pump has to be mounted down stream from that (engine side of switching valve). That means your electric fuel pump has to suck gas up to the drivers seat area before it can push gas up to the engine, your electric pump doesn't want to do that. Best to mount an electric switching valve midway between both tanks, then go directly into your electric fuel pump, which is also mounted midway between both tanks.