Engine Dies

I have a 90 GMC 35000 with a 454 TBI motor. It died today and felt as it was running out of gas. It has duel tanks, both have fuel in them. I switched to the second tank, the truck would not start and all of my gauges pegged out. I switched the tank back to the first, gauges went back to normal and the engine will start but only runs for about 20 seconds at a time. I'm thinking the electric fuel valve may have gone south, but wanted some advice before replacing the valve.

Thanks, John K