hello everyone, I was hoping someone could help me out here... I have a 2002 F150 4.6L 4R70W truck and it randomly dies... I have cleaned the EGR, new IAC, new fuel pump relay, new PCM relay, new DPFE with new lines, new air filter, cleaned the MAF, new spark plugs, new fuel filter, and cleaned the throttle body... it doesn't spit or sputter, it just shuts down... radio keeps playing and everything electrical keeps going... the only thing I can think that would cause this is a crank sensor (which its not showing a code) or the fuel pump... I checked the pressure and it is sitting at idle on 32lbs... it will move to around 40lbs if you give it a little gas and then drop back to around 29/30... I thought this seemed okay... has anyone seen this happen to a truck and not throw a code for the crank sensor? anyone vote for fuel pump? anything else?

 

I'm with yuh on the crank sensor.. - Although those usually just go out and she absolutely won't fire until you giver a new one. I guess a crank sensor could get flaky like you described, just,- I haven't heard of one going out that way. Not yet anyway. Still, the CS would be suspect. - Could be a contaminated connector as well.. If you perform a continuity test with that sensor harness, make sure you move the connector while doing so. Those harness wires can and have separated inside the insulation. Either at the bends or perhaps corrosion from a pin hole

Also, - take a look at the ignition harness over by the AC accumulator. Toward the top of the accumulator. The harness dips there and with time can come into contact with the accumulator. Look for evidence of that happening. Those wires are foil wrapped to prevent any sort of magnetic disturbance. So if the insulation looks disturbed, make sure the foil is intact and/or the wires aren't bare or chaffed. That may create all kinds of havoc with the ig system lol.

 

+1 on crank sensor. I had several go bad on different cars. I just replaced one on my accent. It would just randomly die going down the road, I would pull over and try to start it sometimes it would fire right up sometimes it wouldnt. This also happened on my girlfriends jeep. I replaced both after getting tired of it dying while driving and never had an issue since.

 

thanks for the help guys, I'll be putting a crank sensor on this weekend!

Jbrew - thanks, I'll check those wires too!