Fuel Pump not always priming

[Boise Outlaw]

My rig almost always starts up fine, but every once and a while it needs a double turn of the key, and sometimes it will not prime at all and does not start regardless of how many turns. Hit it with some starter fluid and it starts and runs fine. While running/driving she runs great with no loss of power.

Is there a separate relay that controls the prime?

 

[MrShorty]

Nope, there is only one relay controlling the fuel pump circuit.

A useful test would be to put a fuel pressure gauge on the fuel rail and see how many times it takes for the fuel pressure to come up to spec and to see how quickly the pressure drops off after the pump shuts off. Review the fuel pressure test mini-diary in the under the hood forum for a good description of fuel pressure test procedure.