My friend has a 1987 f-150 with the 5.0.It will run like a champ till he shuts it off.Then it just turns over and doesnt fire.After it sits for awhile it starts right up.What could this problem be?

 

My first blind guess is this. I just had to do it today on an '88. Next, get a Haynes manual & a cheap digital multimeter, and follow the ignition diagnostic procedure. If that doesn't isolate the fault, get a fuel pressure gauge hooked up to it & see how much pressure it's making.