Hey all y'all. Thanks in advance for help here.
2012 F-150 5.0L
Started dying occasionally / rarely this past winter. Now it is dying more frequently. Doesn't like to idle. Idles low and dies or sometimes stumbles, recovers and stays running.
It has a code for crank position sensor so I replaced that. No help and the code came back.
Then I noticed that with the key on, but engine not running, I hear the fuel pump kicking on and off randomly under the truck.
The frequency and random "pattern" of the pump on and off kind of matches the way that the engine stumbles when running.
Although I can't hear the pump run when the engine is running.... it seems to match. So that caught my attention.
I tried to check fuel pressure, but my scan tool won't do that.
I checked fuse 27 and relay 8 they appear to be good.
I looked at the FPDModule. It is a newer style plastic one, not the aluminum one that corrodes away. Although it still could be bad...
Also, unfortunately, I am in the Northeast and in a snow belt. Corrosion is bad here.
And one more clue, when I was still driving it, but it was dying more frequently I thought it was dying at a certain throttle position. I'd call it light tip into the throttle.
Because of that, I was expecting or hoping to see a throttle position sensor code but was surprised to see the crank sensor code instead.
Now I have two issues seemingly unrelated. Can anyone clue me in? Could there be a common cause? What to do next?
Thanks

 

Just an fyi, fuse 27, it's not the fuse that goes bad but the contacts that hold the fuse tight.
They are weak and eventually arc and you loose power to the fuse and FPM.