2010 Ex P0300 crank no start

[worthen86ford]

Truck died in the parking lot but was able to restart. On the way home CEL came on, but made it home. Code reader only has P0300 for random misfire. Tried to start ~20 minutes after getting home and have a crank no start. 2 days later tried it again and it started right up no problem, moved it to my shop and it died as if the key was turned off. since then it has been crank no start.

started with the basics and first think i noted is, that with key on / run position, there is no fuel rail pressure. I swapped the fuel pump relay with the one next to it and confirmed fuses were good. Checked the inertia switch and it was not popped out (assumed to be closed). Took the plug off the fuel pump control module and jumped the black with the brown-white and the violet-white with the yellow-grey. with key in run position the fuel pump comes on and i confirmed fuel rail pressure is good. I thought that with that i should be able to start the vehicle, but again crank no start.

I did check ohms on the 2 camshaft position sensors because of the P0300 code, both read ~350-360 ohms so i figure they are good. Have not checked crank shaft position sensor yet.

At this point i suspect the FPCM is bad, but i still thought that the truck should start with the jumpers. Any ideas on a next step? probably will change out the FPCM tonight regardless.

 

[BigOleFordFan]

Well, having just replaced 4 relays in my 011 EL, which according to my ford tech, any or all of which can cause a no-start condition, with or without cranking...simply because they are all in the same circuit path that goes from the ignition system to the fuel pump and the starter and on to the PCM (Powertrain Control Module).

He said that a failure of any of them can cause a variety of issues, mine was that the "PATS" was being activated & showed the flashing padlock on the dash and therefore resulted in a no-crank/no-start condition, mainly because the failure of these relays interrupts the start-up sequence and overrides the PCM's instructions to send power to the fuel pump & starter...

For now, it's starting right up like it should, but he said that any additional problems would indicate the need for additional diagnostics and they would then start pulling wiring harnesses to check for bad connectors and/or possibly replacing the PCM itself....

Not really looking forward to that, so I'm keeping my fingers crossed

 

[worthen86ford]

Tried the FPCM did not fix it. I do not have an oscilloscope to check signal from the PCM to the FPCM. If the PCM is not calling for the fuel pump to come on, then it may also not be calling for injectors or COPs to fire. Which would make sense why the engine did not start when I jumped the wires to get the fuel pump to come on.

Anybody have knowledge on what would keep the PCM from sending a run signal to the FPCM and possibly other run circuits?

 

[worthen86ford]

Turned out to be the Crank Position Sensor. I went down the rabbit hole of no fuel pressure not understanding how this vehicle's fuel pump theory of operation worked. Basically, the fuel pump comes on for a couple of seconds with key on power to prime the rails and then it shuts off until the PCM sees the engine turnover via the crank pos sensor.