Please post some codes.
Back in the day, we looked at 2 things:
SPARK
FUEL
It was easy back then.
But not today's vehicles.
If it was my truck, and if the BATTERY is known good, and barring engine mechanical issues (like timing chain), the first thing I'd check is the FUEL pressure.
That's the easiest thing to check.
If you have fuel pressure that doesn't decrease, then you can rule out the fuel supply.
But that doesn't mean you have good fuel delivery at the injectors.
Next I would check for SPARK.
Use a fat ground wire connected to a good engine ground, and then loosen all your plug wires at the distributor.
Pull one wire and allow it to jump the gap to you grounded wire while someone cranks it.
Do that with all the wires.
If you have good spark, then you know your spark delivery is good.
But that doesn't mean you have good spark at the plugs.
If both work, then at this point you know you have fuel & spark @ the source.
If either doesn't work, then you have to track down the cause.
No FUEL pressure means possible mechanical failure in pump, or electrical issue (fuse, relay, wiring, connectors etc.).
If no SPARK, that means there's a problem with the electrical supply (fuse, relay, wiring, connectors, etc.), or coil or signal from computer.
At that point you have to check signals from sensors, modules, wiring, etc.
That's where the DVM or scope come into play.
You also need the 'secret knowledge' that the FSM has in it, so you know what the voltage or resistance values are supposed to be.
It's no easy task to find the cause of a NO START when the codes are generic (but what exactly are the codes?).
With more specific codes, you can get a possible start on narrowing down your problem.
