I have a 94 z28 i just bought,,,It was running perfect..Was going down the road at about 55mph and the eng just shut off,,no warning nothing,,no lights came on nothing it just shut off , so i pulled over to try and restart it..it would try to run for about 5 seconds like it was chuggin and just shut back off,,,it will not restart ,,please any ideas,,,need help bad..
Thanks Bob

 

mine did the same thing, but would not restart. turned out to be the coil and i learned this only after replacing the opti. to save the time and money, be sure to scan before doing anything before disconnecting the battery.

 

fuel pump maybe?

 

not the fuel pump its turning on just fine..it just cranks over and nothing
Also before it just shut off..NO ses light came on at all nothing...it just shut down

 

try letting the car cool down for 10min. Your prolly throwing DTC 16 and 36 codes (Low and High res pulse codes) which just means the Opti is shot

 

Id try the coil first(see if your getting spark), im not sure if a light comes on when the coil on the lt1 goes, but in my 89 rs, when the coil went the engine light came on.(needless to say it came on 5 times in about 5 months)

 

Spark and fuel. That is what you need to check first.

 

just replaced coil and icm..still just cranks but wont start..I hear the fuel pump turn on as soon as i turn the key

 

But how long does the fuel pump run? It will prime for about 2 seconds, then turn off. It starts when the PCM sees the low resolution pulse from the Opti. If the PCM can't find the pulse, it shuts the fuel system down.

Might be a good idea to get it scanned, rather than throwing new parts at it. DTC 16 for the Opti will not necessarily turn on the SES light.

Might also be a good idea to check the fuel pressure. Just because it turns on doesn't mean its providing sufficient fuel.

 

UPDATE...Up and running again,,,what happened was the rotor busted apart inside the opti spark.
so replaced complete opti , wires, plugs.
And all back together,,and Bam started right up.