My Suburban has the 350 C.I. Vortec engine.
Three times in the past 6 mos. it has given me problems by not starting.
The engine, fuel pump, the fuel pump pressure regulator, the in-line fuel filter, throttle body, coil, wires, plugs, crankshaft sensor, and both batteries have been changed.
I bought the Suburban knowing it had head gasket issues. The problem started with this engine. It would refuse to start once in a while. Grinding on it for a long time might get it started sometimes. It might not start for a couple of days. Then it would start and miss, backfire, stumble and if you slowly fed it throttle it would straighten out and run fine. Well as fine as an engine with a bad head gasket will run.
Nobody knew what was wrong with it so we started throwing parts at it. A new engine with its own throttle body, fuel pressure regulator and spider injector was swapped in. Still had starting problem.
Then chip in distributor, coil, plugs and wires. Still had starting problem.
Crankshaft sensor went in as engine was changed after we busted the old one.
Then fuel pump, filter, and batteries.
Intermittent starting problem has persisted, although not as often, but the severity has lessened. It will start eventually but will run rough for a little bit and straighten out for a month or two and show up again.
It has refused to start three times since the engine was changed at the most inconvenient times. Twice made me late for work and once for a date.
I keep a half tank or better in it at all times.
The next time it happens I will spray ether in it. If it starts it should be a fuel delivery problem. If not it is an ignition problem.
Anybody care to venture a guess as to the problem.
Thanks for any light you all can shed on this nuisance problem.

 

Have you ever check the fuel pressure? I'd start there. Was the new fuel pump OEM cuz the aftermarket ones tend to be poor quality.

Also in the future, don't post same problem in different sections of the forum as it dilutes the effort to help you and makes searches harder.