Ok, I know A LOT about LT1's since my 94Z loved to crap out alot. This I can't figure out.

It's my friend's car, it wouldn't start (SIX MONTHS AGO) and he asked us to replace the Opti-Spark. SO, we put in a BRAND NEW GM opti-spark and a Mezerie Electric waterpump.

After that it still won't start BUT it's because he neglected to tell us the car wasn't even trying to start. It was his ignition switch. We got that fixed and the car would not fire (it's getting gas and the starter is turning over, just doesn't sound like it's trying to fire AT ALL).

We replaced the ignition coil and it fired right up.

It ran a week and died.

We replaced the plugs and wires which were toast.

It ran great for five minutes (driving) developed a small miss, cut-off, wouldn't crank back up.

Tried to crank it next day, keeps turning over, doesn't fire.

We replaced the ignition module.

It fired right up, drove around the neighborhood, cut it off, cranked it right back up, let it sit awhile, heard a slight miss once, turned it off.

Went to movies, watched "Dodgeball" very funny movie, came home cranked it right up,

drove it 1 mile, started missing,

1 more mile, cut-off but cranked back up,

1 more mile, cranked up after turning it over for a while,

1 more mile it died and will not crank back up.

Pushed it half a mile, it will not crank up.

Pulled the wire from the coil off the opti and grounded it, it fires fine.

It seems the car runs fine for awhile, something gets hot and it doesn't run anymore.

Does ANYONE have ANY clue what this could be???? What else would cause the car not to fire?

We checked all the fuses and they are fine, the opti is plugged in and so are all the ignition coil wires, they are grounded as well.

ANY help is much appreciated!

 

Forgot to mention, hasn't turned on a SES light at all. Also, when I pull the plug off the MAF sensor to trip the light and set the computer into the SES mode it still doesn't crank.

 

There is a relay behind the glovebox that is for the vats or security on the car and it will go out from time to time on some cars and do odd things like you are stating.

This is for a no crank situation that i am diagnosising this for correct.

When it went out on my car the car would run crappy for a bit like it lost a few cylinders and then die. The turn the key and nothing no noise at all.

Not sure if yours soundslike that or not but it could be as I stated.

Just bypass the relay or try a new one and see what happens.

MY car did that for 2 years before i tracked it down. I had to let it sit for and hour or so normally before it would restart. Hell sometimes I would drive it to a store come back out then it would just not start. Big problem when you need to get somewhere.

 

Actually, this one when I turn the key the starter turns it over it just won't actually fire.

I did a lot of searching last night and think it maybe the gas. The car first went bad six months ago and has only run one week out of those six months (due to not being able to work on it for awhile due to his finances).

I am pretty sure it has the same gas it had in it six months ago and it has been sitting all this time. I will drain it and flush it and then put new gas in it and see how it runs.

If that doesn't work I found that "no crank" diagnosis page and will try all of that.

Thanks for the tip on the VATS !

Anyone else have any experience or input? Thanks a bunch !

 

Check the 4 pin opti harness, or the coil connector...have had both of those go bad before. Might just be an intermittent connection.

 

I know you have been through it but read over this. you might have overlooked something

http://mainstreamtopics.com/forum/in...p?showtopic=78

 

Still nothing .

 

is the tach working correctly.......a shorted tach will blow out igntion modules. May run for a while but will eventually burn them up.

 

Is there moisture in the opti? I got water in mine from an unshielded(from rain) filter on my CAI and it would do the same thing. It dried out in a couple of days though with no more problems.

 

seems like teh same thing happens to my car......but it doent happen every mile or so...usually i get to where im going then come backout later and the car starts but runs rough and dies....sometimes it wont crank at all....only when it warms up tho......i got a misfire code....but could never find it.....
deleted teh code........car hasnt gave me a problem yet...
opti coi/icm were all new too

 

try shooting a little bit of carb cleaner into the throttle blades and cranking it up. sounds a lot like when my fuel pump crapped out. it wouldnt die once it was started and running down the road but just sitting it'd stutter and die. i figured out what it was by shooting the carb cleaner in there and it would fire right up. also at the same time it was lazy to start if parked running uphill. just an idea. times this this anything helps i've been there.

 

Well, i found out he hasn't tried emptying the gas tank yet. The car sat for 6 months so I am sure it's bad. He said he had added some gas to it when it first started and ran for that week.

I hope this works. The poor kid lost his grandma right before mother's day and grandfather right before father's day and this car is tapping him dry.

It sounds like it could be the gas but then again it sounded like a lot of things that we replaced and it wasn't.

 

You got a fuel pump problem. He had the problem 6 months ago before the gas was old. Also, if the gas where the problem, it wouldn't start at all. It isn't like there is pools of good fuel and bad fuel swirling around in the tank. Granted the fuel he has sucks and should be changed but I advise you throw a gage on the fuel rails and see what it's doing when you have the problem.

Ask him if he had run the tank real low on fuel and then filled it up around the time the problem occured.