My (new to me) 1995 5.0L F150 will not run on the front tank. When I bought it from my son he said that he just was using the front tank a month or so ago but had switched to the rear when the front went low. I filled up the front (fuel gauge works) but the truck will not start. Flip the switch back to the rear and it fires right up. Am I correct in thinking that the pump in the front tank is bad? It's weird because my son said that he was just running on it.