This indicates fuel switching valve not sealing correct?

[weider1717]

While installing 2 new tanks on my 87 I first installed the right side tank.

now my switching valve seems to stick it takes several times flipping the switch and playing with it to get it to switch. Thats a known issue already.

However, I faintly got ti swapped to the side with the new tank and a little gas in it so I started it up.

noticed gas running out of the fuel line on the LEFT side which didn't currently have a tank installed..

I am not sure which is why I am asking but I don't see why fuel would be coming out of that line other than possibly that switching valve is not SEATING correctly?

am I correct on this? that line on the left side was pumping a little gas and also build pressure on it when you capped it with your thumb.

thanks for any help. Had thought I might not replace that switching valve since the right tank hadn't worked since like 2001 due to bad fuel pump and with all new tanks and pumps maybe with excersie that valve might be ok but if I am right on this I may need to go ahead and replace it.