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Would only start when you let off key now wont start

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would only start when you...
would only start when you let off key now won't start
Submitted: 7 years ago.Category: GM
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Answered in 12 minutes by:
6/25/2010
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Dave Nova
Dave Nova, GMC Technician
Category: GM
Satisfied Customers: 19,452
Experience: ASE Master Certification. GM World Class Certification
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Test voltage on pink wire at coil while cranking the engine, let me know what you find.
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Customer reply replied 7 years ago

9.5 with it still plugged in

GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
What is your fuel pressure reading?
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Customer reply replied 7 years ago
new fuel pump 64 psi forgot to tell you that Dave
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
If you remove the coil wire at the coil and crank the engine, will a spark jump from the coil while cranking?
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Customer reply replied 7 years ago
yes and i get some spark at the plugs it will jump the plug gap but will not jump the tester like my 96 chevy 5.7 pu truck will
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
You replaced the ignition module that is near the coil?
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Customer reply replied 7 years ago
yes this is a tough one
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago

What kind of resistance do you have on your coil wire?

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Customer reply replied 7 years ago
1.59 also put on anew one and tried the old one im lost
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Try backprobing the coil connector pink wire with a paper clip, run a wire from there to the positive battery terminal and try to start the engine. Let me know what you find.
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Customer reply replied 7 years ago
still does not start
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Is spark any stronger with direct voltage to coil?
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Customer reply replied 7 years ago
no same still week
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago

\Try running a redundant ground wire to the Black/white wire at the igntion control module. See if this makes a difference at all and let me know.

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Customer reply replied 7 years ago
no different Dave
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Okay, at the ignition coil, you should have three wires. White, white/black, and pink. Trace the white wire away from the coil connector a few inches and cut this wire. Leave enough slack so it can be reconnected later. Then try starting again and see if the spark is any better off.
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Customer reply replied 7 years ago
Dave are you bypassing the pcm with this cut because i have aused one on the way be here in 10 min it has the same numbers
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
No, this eliminates the tach circuit for the instrument cluster. Just trying to see if this circuit is causing interference with the signal to the coil.
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Customer reply replied 7 years ago
i cut the wire still weak spark did not change pcm
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Changing the PCM will be the next thing I would suggest trying. The PCM must be programmed in order for the vehicle to run. Is the one you are getting pre-programmed?
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Customer reply replied 7 years ago
it is used and it has the same serv.no.09355699 they told me i could just plug it in sound ok
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Should work then. Keep me posted.
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Customer reply replied 7 years ago
spark is still weak
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
How many different coils and modules have you tried? Did you make sure carbon button is in place inside distributor cap?
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Customer reply replied 7 years ago
carbon button is in place on both old and new caps but i have only tried one coil and one module i can 't work on this car again till sat night or sunday can i still contact you again without being charged again
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Yes, I will leave the question open and you can continue to reply to me here. I am inclined to believe the problem is in the coil or the module.
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Customer reply replied 7 years ago
ok thank you i will contact you sunday
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
Sounds good. Enjoy your weekend.
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Customer reply replied 7 years ago
good morning Dave hope you had a good weekend and thankyou for helping me as i am going crazy i pulled the dist. and saw that the pick up coil was rubbing the metal tab that runs through it so iput my old one back on and i had better spark but still not very good it did spit once i turned the dist.and then no spark turned dist. back spark was back still not good changed module back to my old one no spark changed module back to new one no spark Dave i don't know if i told you but as this problemstarted it would not start as long asthe engine was cranking only when you let go to stop cranking would it kick and fire up andnow once inawhile when letting go of the key i see a bright spark im using a spark tester with clear glass on it could this have anything to do with the ignition switch
GM Mechanic: Dave Nova, GMC Technician replied 7 years ago
I was originally thinking ignition switch, that is why I had you run a jumper wire from the battery to the pink wire on the coil. Now that you have the problem with the pickup coil fixed, Try running a jumper wire from the battery positive to the pink wire once again to see if it will start. Let me know what you find.
Dave Nova
Dave Nova, GMC Technician
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Satisfied Customers: 19,452
Experience: ASE Master Certification. GM World Class Certification
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Customer reply replied 7 years ago
Dave i went and bought another coil that was the problem the first new coil i bought was bad THANK YOU XXXXX HELP
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