Problem starting my truck

Engines need several things in order to start. They need (1) fuel, (2) air, (3) compression, (4) sparks, and (5) 1-4 have to be on time, in the correct strength/amount. Unfortunately, when you get over 150,000 miles on any vehicle, any of those could be the problem. The most common causes are with (1) and (4).

I would start with simply listening for the sound of the fuel pump coming on. When you turn the key on, without turning the engine over, the pump should come on for two to three seconds. It makes a humming sound. If you can, get a helper to turn the key on while you listen for it. If you do not hear it come on, try tapping on the bottom of the tank with a hammer or other blunt object immediately after the helper turns the key on. If you then hear the pump come on, then you need a new fuel pump. Simple as that. You freed up the brushes in the electric motor inside the pump. This is a very temporary fix (might give you an hour or two of running time).

Just because the pump receives power and comes on, does not mean that it is pumping enough. We will circle back to checking the pressure output later on, if necessary.

If the pump is coming on, the next easy thing to check is for sparks. You can do this with a tester that is available at AutoZone or any other auto parts store. Here is a link for one on Amazon: https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6/ref=sr_1_3?ie=UTF8&qid=1501325755&sr=8-3&keywords=spark+tester

Basically, you pull the plug wire off of the ignition coil (also pictured below) and plug in this tester between the coil and the plug wire. Then get someone to turn the key while you observe it. If it flashes, then you have spark. Check all of the cylinders.

Let us know and we will go from there. There are more advanced tests that you can do for free or very cheap. We will go through them if needed.