When starting my e350 motorhome 460 should both the lift pump and high pressure fuel pump come on simultaneously ? Motorhome was running nicely and came to a stop. Haven't been able to start is since. Sounded to me that it ran out of fuel. I checked fuse, relays and inertia switch and all is good. I can hear the pump in the tank cycle but the pump on the rail makes no noise?? Any idea's ??