lt1 cranks, wont start
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 94
Likes: 0
From: Michigan
lt1 cranks, wont start My 96 trans am has been givinf me an absolute fit.
Cranks but won't start
Been Going in deep with diagnoatic and scan tools.
The motor has compression
Fuel is over 40lbs at the rail with pressure test, can't trst it running because it will not start. If I open the TB after start attempts it smells strongly of fuel so I believe the injectors are firing. Thats my next test tomorrow
Optispark signal cionfirmed with oscilloscope.
ICM tested, realised testing it when it's cold is not definitive, replaced with new Ac Delco ICM. No start condition unchanged
Coil wire to distributor tested under 5k ohms, withing factory spec.
Ignition coil also tested good.
The only code is for the ICM which is being set from excessively trying to start the car.
Borrowed a 6k doller scan tool, which was very neat. But revealed no clues.
Out of ideas, running out of money. Any thoughts might help
Cranks but won't start
Been Going in deep with diagnoatic and scan tools.
The motor has compression
Fuel is over 40lbs at the rail with pressure test, can't trst it running because it will not start. If I open the TB after start attempts it smells strongly of fuel so I believe the injectors are firing. Thats my next test tomorrow
Optispark signal cionfirmed with oscilloscope.
ICM tested, realised testing it when it's cold is not definitive, replaced with new Ac Delco ICM. No start condition unchanged
Coil wire to distributor tested under 5k ohms, withing factory spec.
Ignition coil also tested good.
The only code is for the ICM which is being set from excessively trying to start the car.
Borrowed a 6k doller scan tool, which was very neat. But revealed no clues.
Out of ideas, running out of money. Any thoughts might help
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 94
Likes: 0
From: Michigan
Yup, i pulled spark plug #1 and checked for spark. After getiing no spark at the plug I tested the plug wire for continuity and confirmed the wire was good.
Afterwards I did the same test to the Ignition coil wire and with no spark from the coil to the wire again confirmed the coil wire was good and then proceeded to test the Coil and the ICM. Both we're fine but I was suspicious of the ICM as I've heard several accounts of ICM's testing as operational when cold and then failing as they heat back up. With that in mind I purchased a new OEM ICM and the no start condition persists
Afterwards I did the same test to the Ignition coil wire and with no spark from the coil to the wire again confirmed the coil wire was good and then proceeded to test the Coil and the ICM. Both we're fine but I was suspicious of the ICM as I've heard several accounts of ICM's testing as operational when cold and then failing as they heat back up. With that in mind I purchased a new OEM ICM and the no start condition persists
Go here and look at the "crank but no start diagnosis". It might help.
https://www.facebook.com/groups/LT1Nation/files/
https://www.facebook.com/groups/LT1Nation/files/
Last edited by Purple Poncho; May 17, 2019 at 01:39 PM.
Go here and looks at the "crank but no start diagnosis". It might help.
https://www.facebook.com/groups/LT1Nation/files/
https://www.facebook.com/groups/LT1Nation/files/
