I have an 87 chevy 1/2 ton pick-up with factory dual gas tanks. The tanks wont switch from one side to the other. They quit working a few weeks ago. I've had the dash swich changed, both in tank fuel pumps changed, switching valve changed, wiring harness,at the switching valve, checked. Fuel lines checked for blockage. What else is there? HELP. Thanks.

You could have a broken wire somewhere in a harness. You need to get someone in there that knows how to properly diagnose electrical problems and stop throwing parts in. You probably could have gotten it fixed originally for less money than you've wasted in parts. <img src="graemlins/nono.gif" border="0" alt="[nono]" />