Please need some help . Was driving down road and the truck check engine light came on and truck just stopped. Sprayed some stuff in intake and it will start and shut off so I know spark is good so I thought it was the fuel pump . Changed out fuel pump and that wasnt it also checked fuses and relays and they appear good . So now I think it is the PCM so replaced that and still doesn't start. With key on there is 5 vdc at fuel pump. what exactly is that telling me ??? Maybe inertia switch is good? Kinda lost for the next steps

 

How many miles on your 2000?

What brand of fuel pump did you buy?
There have been reports of "dead-out-of-the-box" new pumps.
It's claimed that Motorcraft parts are tested before shipment and can thus be a better buy.

I don't know what voltage the pump requires.
What does, "Maybe the inertia switch is good?", mean? Have you checked it? It's behind the carpeting beneath the glove box.
Were you bustin' it on rough roads when the truck stopped?

 

It came from Advance auto a complete unit. I figured since there is 5 vdc at pump then the current is going thru the inertia switch