Check for fuel pressure when it won't start.
If there is no pressure, two things come to mind. Listen for the fuel pump to run when you turn the ignition switch to "run". I can't remember when it should turn on, but for sure it should be on during engine cranking. I believe it gets power through the oil pressure switch, so be sure your oil level is correct.
A fairly common problem with older trucks with metal gas tanks is loss of ground for the fuel pump due to rust buildup between the tank and the mounting straps. You can find that by using a test light. Be sure the light is grounded to a good clean body ground, then measure for voltage on the tank itself. It might be necessary to do this while a helper cranks the engine. If the test light lights up, the bad ground is preventing the fuel pump from running.
Drill a small hole in the flange of the tank outside of the welded seam. Run a self-tapping screw into the hole and attach a wire to it. Attach the other end of the wire to a clean and shiny spot on the body or frame of the truck.
Saturday, March 20th, 2010 AT 4:31 PM