Okay, that would be an issue with the one way check valve in the pumps pressure line to the engine. The long crank is because the fuel is draining back out of the lines. When you first turn on the key the pump will run for a couple seconds to make up for the normal pressure loss, in your case the normal pressure isn't there so you crank it, the oil pressure signals the ECM which turns on the pump. It then has time to fill the lines and the truck starts. Then if you start it soon after it will start because there is now fuel in the line.
Easy test for this. Wait a day or whatever time it takes for the long crank start. Now get in and only turn the key to the on position, don't try to start it yet. Turn the key back off, then on again. Repeat it once more. Now try to start it. If the pump is losing pressure then this will run the prime cycle three times and it should start up like it should.
If it still has to crank then go find the fuel pump relay under the hood and be sure it is working when you turn the key on. It is very possible the pump is starting to fail and causing the relay to as well.
If the first test makes it start up then you need to replace the check valve in the fuel feed tube.
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Friday, December 28th, 2018 AT 5:19 PM