My truck cranks but will not start

Have a helper crank it, if it still cranks, while you check for spark at the spark plugs. Take spark plug wire loose, use a known good plug or spark tester in the boot, don't pull a spark plug from engine. Ground metal part of spark tester to metal part of engine, watch for spark, engine cranking. If you have spark everywhere, use a gage and check fuel pressure. Check for applicable trouble codes. You should be able to check mil codes, yourself, You turn key just till the dash lites come on, no further, cycle key, on--off, on--off, on. You are looking for two digit codes.

If you think it is a valve timing issue, do a compression test.