4.2 liter F150 starts then dies

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This is concerning my little brothers truck. He drove it to work today, ran fine. This afternoon he went to leave and the truck starts, idles smooth as butter for 5 seconds max then dies.

Truck is a 2008 F150 with the 4.2 liter and 55,000 miles.

Before I could look at it he and his boss replaced the fuel filter as the original was on there and it was time anyway. The battery was also replaced, also original and bad (eye was red). No change after these were replaced. Fuel in the old filter was dirty.

Checked the fuel pump driver module as corrosion is common on these in the F150, no corrosion. Fuel pump also runs from when key is turned to on until it dies.

All fuses are also good.

It got dark on us so I just brought him home. Tomorrow we are going back to further diagnose or tow. The only other things I can think to check is the MAF, and fuel rail pressure sensor. Anything else can be checked while we are poking around? Any ideas on what could cause this? Im open to trying almost anything to fix it where its at. Thanks in advance for any suggestions.
 
Dirty IAC valve and passage? Sometimes when the IAC valve and passage are dirty, the engine will idle properly when the idle speed is set high, but problems happen when the engine goes back to the warm idle speed.

Some DBW systems don't use an IAC valve. The whole throttle body determines idle speed. If that is the case, make sure the throttle body isn't dirty.
 
Originally Posted By: 71Chevyguy
Does this truck have factory anti-theft? Try using another key if you have one and see if it keeps running.


I did bring the spare key when I went out there. Tried that immediately and got the same result. I forgot to put that in my original post.
 
The ford anti theft system of that era would disable the starter as well as the ignition. You still get fuel though. Don't think its PATS acing up.
 
If you try several times in succession to get it running, does it start and run for the same amount of time and die every time? How does it quit, does it slowly start to stumble and eventually stop running or does it run normal right up to the point that it immediatly dies?

Any OBDII codes?
 
Can't tell about the codes. It runs great and just dies, off the cliff so to speak. If we play around with the accelerator it may stumble before dying but left to run on its own it just dies.
 
Yeah, I was gonna say, you can unplug the MAF. Itll run off of speed density using the ESM (EGR System Module) to feed it MAP info.
Only thing is it'll shift kinda funky. I think it overestimates load, for safety.
You can also unplug the cam sensor. Itll just run the injectors in batch mode instead of sequential. Giving it half a load of fuel on each cylinder everytime the #1 comes around on the crank.
Sometimes its better to have no info for a given sensor than bad info.
Crank sensor is about the only one it can't live without. Since it was firing intially I didnt think it was that, anyway.
 
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