I just put a new 350 tpi GM crate mtr in my 89 iroc, got it all back together and she started right up, set timing at 6 btc. the problem is when you shut it off, it will not start again, turns over
, has spark, just will not start, seems as if it is getting no fuel.
let the car sit afew hours and it starts back up. vac is at 18 inch
but seems to drop down to 16 while warming up, could a vac
leak be bad enough to keep it from starting up?:

 

Welcome aboard.

A few things on these cars can create a no-start condition when the engine is hot. 2 of the more common ones that occur are the igntion modules failing or the phenomon known as "heat soak."

What does the car sound like when it doesn't start?

 

verify the fuel pressure at the rail and let us know what it is,
??PSI

 

1st, the car cranks and doesn't fire, sounds like no fuel,
2nd, the fuel presure is 46lbs

 

Ignition module. Have it tested and, most likely, replaced.

 

leaky fuel injectors will also cause this condition.

 

When you say it is turning over, is it turning over slowly or at the same speed as when cold. If it is the "heat soak" problem it will turn over slowly, if it turns over fine, then it is another problem. My car showed similar symptons when I had leaking injectors like Josh said.

 

the car turns over fine, the same as when its cold.
this thing with leaking injectors, Its not like the car sits for
a while and then we try to restart it, I mean you shut it off
and turn it right back on, and nothing, just cranks and cranks.
how much leaking does it take to flood.

 

When your having problems with it not starting, did you pull ALL the plugs and look them over? Try giving us a little more detailed info please. It is real hard to help with the lack of info/facts given.

 

dude, seriously, i really dont know how to explain it, im sure someone on here could but i had the EXACT same problem, it only happened right after i turned the car off. I changed the injectors and it fixed the problem.

 

Sounds like it could be the ignition module as Stekman mentioned. When mine died it would still fire the coil but would not send the reference pulse to the ecm to fire the injectors after I would shut it off when hot, had to let it cool down for 20 minutes to get it to fire the injectors. It would run as long as needed unless it was shut off. Might want to get a noid light or a logic probe to see if the injectors are getting pulsed on restart.