I have heard lots about the fuel pump check valve problems causing hard starting in the mornings.
I suspect that is my problem. How do you check that valve and is there any fix, other than replacing the pump?

The FSM does not mention or show any diagram with a check valve so unless you are talking about the fuel pressure regulator in the fuel rail system, it must be internal to the pump.

Typically the check valve is in the outlet end of the fuel pump, but not always. There is also generally an overpressure relief valve in the pump as well.

Don't get too hung up on "factory service manual says", as it's published by humans, and is far from faultless or all encompassing.

How do you check that valve and is there any fix, other than replacing the pump?

The fuel pump does indeed have a check valve and it should hold pressure over night.Before you start it in the morning turn the key to the on position and leave it there for 15 seconds.Do this a couple of times before you start it.That should turn the fuel pump on and pressurize the system. If it starts right up you have a fuel pressure problem.If that is the case there are two things it can be. The fuel pump or a leaky injector.My money is on the fuel pump.You used to be able to jump the fuel pump from the diagnostic box(drivers side next to intake) by jumping Fp and B+ but I looked in mine and there is no conector in the Fp slot.

Theoretically, you could take the pump apart and replace the check valve pieces, provided you could find a way to buy them. Otherwise, you just replace the pump.

You can check fuel rail pressure before you go attempting to start the truck. If you've got no pressure in the rail, something has leaked it out.

You've got three different things that hold the pressure in the fuel rail. The check valve in the pump, the pressure regulator at the other end, and the fuel injectors themselves. If any of those three leak, you will lose pressure in the rail and have a longer cranking time getting the truck to start.

If you turn the key and let the fuel pump cycle for 15 seconds a couple of times and it still cranks a long time, does this mean you have a spark (maybe starter) issue, not a fuel issue?

No, you can't make that far a leap. All you've done is pretty well ensure the problem is not the fuel pump and fuel pressure. You could still have a difficult time starting because of dirty injectors, manifold vacuum leaks, air meter problems, etc.