Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
first off I'll admit I don't know this engine. So I'll offer my 2 cents worth of generic info and Opt out to keep the topic open for other experts who may know more.
To easily find out if it's a fuel delivery problem, spray something flammable like starter spray or brake cleaner (the flammabnle type, not the "safe" stuff) directly into the air intake through the air filter box. A 3 second spray should suffice. Then immediately turn the key and try to start the engine. If it tries to start and maybe runs for a second or two, you'll at least know you have spark, and can concentrate on the fuel system instead.
Vapor lock shouldn't happen on a running engine. The fuel flow cools everything enough. It's when you park a hot engine, that you may get vapor locking.. but it's not very likely in modern systems like these in my opinion.
Check fuel pump fuse. Listen for fuel pump running when you turn the key on or to start.
I can't remember if the pump is supposed to come on with teh ign ON, or only during cranking. It could also require oil pressure to build high enough first.