While cruising at 65 mph the engine suddenly died. Wouldn't restart. No fault codes registered, either fuel or ignition system. When main pump is hot wired the engine runs. Tried known good relay but still won't start. Doesn't have power to pump from relay when cranking. (Tested at the fuse/relay board.) Fuel pump ground is good. When a non powered test light is conneted to the yellow wire with a black stripe on the bottom side of the relay, (key on) I can hear the main pump start up, engine will then run breifly. What causes the relay to close the circuit to the pump? Anyone have an idea why this will not start without hot wiring the main pump?