I have a 93 Z28 with 110,000 miles on it. Was running great, then it started being tough to start when it was hot, acted like it was flooded and when it started would clear out and drive fine. Started and ran fine when it was cold. After a couple days it would not start, and when it finally did it idled decent, drove the car about a half mile and it started acting like it was loading up. Parked it and it will not start at all now.

the following symptoms prevail..............

We found a small crack in the air intake elbow between the MAF and intake and replaced it:

You can hear the fuel pump pressure up when you turn the key on:

It cranks over fine:

It smells of raw fuel, none is leaking outside the motor:

Oil does not smell of fuel nor over full:

It acts like it starts for a second but dies:

It acts like the engine is flooded as you try to crank it:

It has good spark from the coil, good spark on the 3 or 4 plug wires we tested:

NO SES light or codes, NONE:

Proper fuel pressure:

All the injectors are pulsing when tested:

Sometimes while cranking it coughs back through the intake, but not always:

Changed the plugs and wires and still no difference:

Anyone got any clues ?

Is there a way to test the OPTISPARK since that seems everyones first words and the standard answer much like REBOOT your PC when you have troubles with windows.

Is there anything that would cause it to continue to dump fuel to the engine like a cold start solenoid or something ?

 

If it is coughing through the intake sounds like you may have your plug wires crossed. That doesn't explain the fuel smell but its a good place to start.

 

The wires and plugs were changed after the no start condition in an effort to fix it.

 

Ditto, if it firing through the intake its a timing issue.

 

Have the injectors been tested to see if they leak?

 

i had the same thing occur in december on my 95 one day it started running rough and it seemed want to run but anything more than idle it would cough and idle down to 200rpm either die or sit and sputter,guess who was acting the fool MR.OPTI
you can still have spark(not a good one)with the opti going bad,of course you may be experiencing something totally different than i did!
hope this helps you out ....................

 

I would also agree that more than likely it sounds like an OPTI on it's way out.
But before you go and replace it, just double check that the plug wires aren't crossed at all.

 

injectors are not stuck, no wires crossed or wired wrong.

It is not popping back constantly through the intake during cranking, just once in awhile due to the buildup of gas. When timing chains go south it will pop back constantly during cranking as the entire valvetrain is out of time with the ignition, this is not the case here.

Is there anyway to test the opti ?

Is the timing adjustable on these or checkable ?

 

This site is your friend http://shbox.com/1/4th_gen_tech2.html#opti_test