Engine turns but will not start

Hello,

Ok, when you turn the key to the ON Position without trying to start it can you hear a hum from the back of the vehicle that lasts for about 3 - 5 seconds? If not then could be a bad fuel pump (in-tank), Fuel pump relay, or fuel pressure regulator.

Also did or was the check engine light on?

Why the high octane gas? That is much harder to ignite and can add to the problem. Have you checked for spark and fuel pressure? What about diagnostic fault codes?

Hi there,

The idle speed is controlled by the ECU and an idle control motor, normally this is a faulty idle control motor, a scan may pick this up and any other unresolved fault codes, start here.

Mark (mhpautos)

The IAC is controlled by the PCM, but in my experience they rarely show up with any codes. Basically Ford did not put a return signal circuit on the IAC to determine actual position vs commanded so the PCM doesn't know if it is not responding to the commanded position so ti can cause the engine to just shut off due to insufficient air flow.

I attached the process to replace it and I would just go ahead and do that and retest.