Hi, i have a 2003 f150 2WD crew cab with a 4.6 V8 engine it has 178,000 miles on it. the other day after I started it to leave work it died on me without hesitation almost like the ignition switch was turned off I tried to restart and it would turn over but wouldn't start so I switched the ignition all the way off and it started right up, going down the road it did it again. if I try to restart without turning the ignition all the way off it won't start but if I turn it all the way off it will start up first try, it has done it a couple times since and its the same way every time, do you guys have any suggestions on where to start. my check engine light has been on for some time for something else so I don't know if it picked up a code or not I don't have a code reader to see if it has a new code, thanks

 

fuel pump would be my first thought.

 

If you have to rock the ignition switch like that, it is the first suspect.
Then the fuel pump relay next.
Good luck.