My truck wont start it will turn over but dont start

Remove plug #1 and turn the engine over by hand until the piston is at the top of its cycle. Check the crankshaft timing mark and distributor rotor location. The timing mark on the crankshaft should be at 0 degrees. The rotor should be pointing at the number one plug tower on the cap. If not, rotate the engine another 180 degrees and bring the piston back up and check again. IF the mark and/or rotor don't line up, you have a timing issue. If the rotor is close, you can turn the distributor. If it's more than 20 degrees off, the timing chain is off.

Ok. Next check fuel pressure and compression. Compression should be around 120PSI and vary by no more than 15%.