Hi All,
Thanks for reading. 99 F150 Lariat 4wd 5.4L. Went to Sears then when came back truck would not start. As long as the ign key is pushed it sounds like it wants to start but when I release the key it won't continue. Ran fine up to this point with no issues. Any help greatly appreciated before I start to tinker.
Thank you.

 

So its turning over? If so, try to turning the key to run, do not crank the motor, and listen to see if the fuel pump is turning on. If not theres a start

If its not turning over, are you getting a single click, no sounds at all, lights cutting out? Have you checked the battery?


-Matt

 

Engine turns over and sounds like it wants to start but won't. When key to on I hear the fuel pump go until I think it reachs pressure then stops. Maybe F.P is good but something electrical?

 

I had an issue with the crankshaft postion sensor. It is located down by the ac compressor and the block on passenger side. Mine must have been loose or something, but I disconnected it, then reconnected and she started. There's also the fuel shut off safety thing on the passenger side footwell, behind the plastic interior piece. I can't remember it's name, but it cuts fuel in case of a hit or drop. I doubt that's it, but you never know. Good Luck.

 

If that doesn't work - Start with fuel system diagnostics. Check the Inertia.

 

Thanks everyone. I check the sensor first then the shutoff switch and return with results.

 

what's the "inertia?"

 

Its a switch normally located near the passenger kick panel that shuts the fuel pump off during a collision or rollover. It can be reset. Check to make sure it hasnt tripped for some odd reason

 

The "inertia switch" is a fuel cut off switch located behind the passenger kick panel. When the vehicle is in an accident and its "inertia" goes from a lot to nothing real quick the switch triggers thus cutting off the fuel supply.

 

sounds like it could be the crankshaft position sensor, see if the sensor is nice and tight, you can also remove the sensor to clean the crud off of it. next i would check fuses, then maybe hook the truck to a scanner and see if your throwing any codes. good luck to you