My 2017 F150 (5.0) is experiencing extended crank time (5-10 seconds) after the engine gets warm and I stop, letting the truck sit for greater than 2 hours. If it sits over night it starts fine. Experiencing no performance issues once it starts. I can mitigate this issue by opening my hood and leaving it open until the engine is cool as soon as I park. Mechanic said fuel pressure are fine and hold. New cylinder head temp sensor, new purge valve, new fuel pump driver module. 165,000 miles. Thank you!

 

You checked your spark plugs yet? Attach photos here if possible.
There is something else you can test easily. Before a warm start, use a voltmeter and get the battery voltage, continue to monitor the voltage change during cranking, and what's the cranking voltage? Higher temperature = higher resistance = higher voltage drop.

 

When the engine is warm and typically would take longer to fire up and start, try holding the throttle pedal to the floor and see if it starts sooner.

 

The spark plugs have been checked and were all good. The battery is only a couple months old. Could that still be a issue?

 

I didn’t notice a change. I propped the hood open after driving twice today and let the engine cool. Started perfectly. The 3rd time I left the hood down, came out around 2 hours later, extended crank. Could it be a heat soak impacting the fuel rail?

 

When you do the cranking test you are testing the battery plus the cable(s). That's why I mentioned easiest test you should not ignore. If your cranking voltage is under 9V you will definitely need to inspect the B+ connection to the starter, the ground cable of your battery, and the other to the engine block, when the engine is too warm, you get higher voltage drop, too low that can take a long crank to be able to start it up.
Why do most tuned cars use to 1 or 2 steps colder spark plugs so that matter too when it's too hot but you said you checked and they were all good.

 

That actually makes sense! I’ll try it and see what I get. Thank you!

 

So far, we don't know if it is a fuel problem, electrical problem ,intake problem or an ignition problem.

We need to eliminate them one at a time.
When it won't start when warm, pull one of the plugs and see if it is wet or dry.That should tell us if there is a fuel supply problem, or an ignition problem.

What we find there will determine where we go next, OK ?

 

Pulled codes of P0316 and P0304. No check engine light. This was during one of the extended start times. Voltage didn’t change much during starting. Went ahead and had a system check with the scanner performed on the battery and checked out good.

 

I was a little surprise when you pulled only P0316 and P0304. Since you insist your spark plugs are in good condition, next thing to check is the pcv valve, just remove and shake it, can you hear rattle noise in accordance with your shaking movement. At 165k miles your pcv valve (a maintenance item) should have been replaced 3 to 5 times already. At under $10 It's one of the cheapest car parts yet with an important role, you don't need to get motorcraft just replace it every 30k, you also don't need to buy the hose (just remove and clean).

What's next? You said you have good fuel pressure and with new fuel pump. How about your fuel injectors you ever thought about leaking? Buy the o-rings upfront before you remove any for inspection.

Camshaft position sensor can also be the problem you should have a look.

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