95 LT1 wont start..need help
 

Ok so my brother bought a 95 LT1. When it was purchased we were told it would need an optispark replacement. After doing my homework for a week or so i swapped out the opti last night. I put everything back together and the car fired over for about 5 seconds and died. Today i came home from work and tried another battery because the other was dead, and the car fired over and died a few more times. does this sound like an optispark issue? we got the gm unit brand new and its an M6 car if that helps.

did you replace the firing order correctly?

test fuel pressure?

edit .. yea, firing order is a good thing to check also....

yes i made sure the order was correct. as far as fuel pressure where is the schrader valve located on this car?

behind the intake off to the right side i believe. make sure your plug wires are on correctly as well

this car had msd wires with each of them marked already, so reinstalling them was a snap. i think its a fuel issue. almost like the pump turns off on startup or something. it does prime however

if it primes and has pressure at the schrader valve then the pump should be good. iirc the fuel pressure should be like 35 lbs or so...not sure, that could be my old sc tbird im thinking of too. did you replace the optispark correctly? also are you sure the optispark isnt one of the other designs, i know they redesigned it in 95, so check that too

im pretty sure i replaced it correctly. i read it a hundred times..i hope i did.

this is the exact opti we got-

http://cgi.ebay.com/ebaymotors/ws/eB...m=120259733243

go check the door jamb on the lt1, im willing to bet its a late model 94 sold as a 95. double check the firing order too....never trust other peoples marks they couldve been marked wrong in the first place

http://shbox.com/1/fp_reg.jpg

could have been wrong from the previous owner maybe. Just to make sure ...

http://shbox.com/1/opti.jpg

this guy is in the right frame of mind

thanks guys. ive been combing cz28 and have found people with similar issues it turned out to be the coil and icm..does this sound right?

yeah definitely trace the wires. check the fuel pressure. isn't the only difference between the opti's is the 95's and up were "vented" with a rubber hose from the intake? you could do a compression check...bet thats fun on LT1's. start from the basics up. wouldn't hurt to through 5 gallons of gas in it. gauge might be effed up.

if you think so...check for spark. pull a plug wire off and crank.

dude the car ran before you took off the optispark. now it doesnt.
optispark is where your looking. stop trying to replace a million things and
take it one step at a time. im still willing to bet its firing order:nod:

he never said it ran...

well ill be damned your right :rofl:
why the hell would you buy a non running lt1
when nice lt1s are super cheap and everywhere

yeah i would go and check for spark then. this is where it gets fun.
a dvom is really helpfull in this situation...got one?

because my brother wanted it...because he got the car for under 3k..and its fully loaded...and i trust the guy he bought it from...and we were told about all the issues with the car...

so it fires then dies right out...its probably something stupid


anyway, we got a some new parts and tomorrow hopefully if its not raining i can run a fuel pressure check and then check spark, replace some stuff, etc, etc

i had a similar problem with my 89 trans am and it turned out to be one of my fuel injectors had a short in it...just throwing it out there

can you keep it running if you hit the gas? When it does start does it sound horrible then die?

If you have disconnected the battery then the computer will have to reset the idle, so this or the ICM could be the stalling issue.

There is a sensor in the front of the water pump that is the ECM's coolant temp sensor. If it's not connected or faulty it could cause problems.

You should be able to keep it running by pressing the gas peddle, if it's stalling with the gas depressed then I'd look elsewhere for the problem. MAS, MAP etc,

ok im getting right around 40 psi of fuel when cranking and when the pump is primed. the coil has been replaced and it runs a few seconds longer but still dies

have you tried to coax it into running with a foot on the peddle? does the fuel pressure drop off when it stalls? did you check the wire routing? check vacuum lines and such?

yup checked everything

then changed the ICM and it fired right over, sounds great. thanks everyone

:lol: i was gonna say, when my opti went it took my ICM out about a week later. Did the same thing as yours. My coil went, took out the opti, then the ICM went a week later. Glad you figured it out.