Went out and started up the 94 Z this evening. Started up, but then died immediately. Can't get it to fire up. It cranks, is backfireing through the intake but won't crank up. When it does backfire, it acts like it wants to turn over for a second and then nothing. Just stops dead cold. I pulled off the intake elbow and when it backfires, it shoots a flame out about 6 inches. I also smell gas as if it's flooded, and I can hear the fuel pump buzzing along so it's getting fuel. I put an old timing light on the coil wire and I at least get it to blink, so it would appear that spark is getting to the opti. Any ideas on what else this could be and how to check it. New to the LT1 world so take it easy on me...

 

Sounds like what mine did. the Accell 300+ shorted out, taking the coil, ignition module and the opti with it.

 

Do a search in here for "shoebox". He's a member here. Click on his tech link and you'll find all kinds of schematics and info for testing your ignition system. Until you take it one step at a time there are a lot of things you can guess at. Just keep it simple, don't jump to conclusions and start buying new parts. Your getting the raw gas/ flooded smell because the timing isn't right for some reason and it's not burning all the fuel. It might be the ICM, PCM, opti, coil or a wire connection. If there is an aftermarket ignition on the car ie: holley, accel, msd, then bypass that system. Be prewpared to buy new plugs and or O2 sensors if you fouled them out. Chances are that you may have or will before you're through. It's not all that hard to do any of these things on these cars really, just takes time and patients. Good luck.

 

Exact same thign happened to my 94 Z a month ago and I traced it back to the coil and the inition module were both bad. Get a spark tester and test to see if the coil is giving spark.

 

Weird deal. Went out this am and the car started up straight away. It rained a good bit here yesterday and I drove through some water on the street (about 4"). Could it be that water got into the Opti? If so, is there a way to ensure that this doesn't happen again? Or should I be concerned that it was something intermittent and not drive it far for a while?

 

Sounds like your coil got wet. In the future, if you get a constint, high RPM stumble or car runs like crap after it warms up(just some of the MANY things a bad opti does), it's a good chance your opti optical sensors are rusting. Check your resonance tube, long tube off of the intake elbow for water.