I have a 93 f150 with a 351w. I was driving today and my check engine light came on when I parked and turned off the truck to check the codes I turned the key back to the on position the light was gone and every time I drive it turns back on. But when I restart it it's off. I have absolutely no idea what's going on and it's starting to irritate me so any help would be really appreciated

 

So check the codes dude.

 

/\ He about summed it up pretty well.

 

It's not pulling any codes

 

Then you aren't doing it right, you would at least get 111 codes

 

The light won't turn on unless I'm driving it. When I'm stationary the light goes off

 

Just from personal experience cel comes on after ~5 minutes of driving then dissapears upon restart is usually o2 sensor related, it takes the computer changing cycles (open/closed loop) and three attempts at altering fuel mixture to pop the code.

 

You can still pull the codes, see the sticky at the top of the forum, grab a short piece of wire or paperclip. connect the upper right corner of the house looking connector to the one holed white connector right next to it in the holder on the drivers side close to the hinge.

 

Damn forgot about the O2. Thanks bub

 

you still need to pull the codes, that is only one possibility, though it's probably your problem, you should still pull them to verify!