If you're experiencing a problem, it's likely something *other* than the engine shutting off – perhaps you're experiencing one of these:
* The engine is still running after you've turned the key off: This is a serious problem and could be caused by a faulty ignition switch, a problem with the starter, or a short circuit. This needs immediate attention from a mechanic.
* You're experiencing a delay in the engine shutting off: A slight delay is possible, but a significant delay suggests a problem with the ignition system or a related component. Again, professional diagnosis is needed.
* The engine is unexpectedly shutting off *while* driving: This is a different and more dangerous issue, potentially caused by a wide range of problems from fuel delivery issues to electrical faults or even serious engine problems. This requires immediate professional attention – do not drive the vehicle until it's checked.
* You're confused about how the ignition system works: If you're unsure how your F-150's ignition system works, consult your owner's manual.
To clarify the issue, please describe what's actually happening. Are you experiencing a problem beyond the normal engine shutoff when the key is turned off? Providing more details will help in determining the cause.