LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Please help lt1 wont start

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Old 09-11-2011, 06:49 AM
  #16  
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Re: Please help lt1 wont start

1. Have it scanned for codes again, remember the '95 has a OBD ii port but is OBD i. (thanks Injuneer) See what the codes reveal. The codes that are found are going to be your best source of information on where to proceed next.
2. Recheck your connections, look inside for corrosion. I used electronic parts cleaner and then put dielectric grease on the connector ends.
3. Make a 'noid' light and check the injector pulses. Check the under hood fuses, there are some for each injector bank and others of course. I'm not sure what fuse Final03 is talking about, tho.
4. The ground for the PCM is on the passenger side, down low. It should be bolted to the block. It is black 16 gauge wire with a white stripe. Look for the harness that is by the starter. This also will keep it from starting.
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Old 09-11-2011, 09:02 AM
  #17  
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Re: Please help lt1 wont start

Originally Posted by T/A 95
okay guys i got a new update
..... i check all my optispoark wires to pcm and found everything perfect.... also checked my coil and i am getting spark and fuel... also check the vats system...... all good but car still just cranks and cranks but wont fire up... new icm again.... i am so lost.... what next?
How did you check the wires from the Opti to the PCM?

How do you know you are getting fuel? What is the pressure?
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Old 09-11-2011, 11:17 AM
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Re: Please help lt1 wont start

If you're getting spark, squirt fuel in the intake while someone cranks it over.
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Old 09-11-2011, 07:34 PM
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Re: Please help lt1 wont start

Originally Posted by T/A 95
okay guys i got a new update
..... i check all my optispoark wires to pcm and found everything perfect.... also checked my coil and i am getting spark and fuel... also check the vats system...... all good but car still just cranks and cranks but wont fire up... new icm again.... i am so lost.... what next?
check your opti pig tail to your opti. i had a problem when i installed new opti, when i plugged it in i bent a prong on the opti and it would run for a while then just die and not start. then i noticed the bent prong, bent it and replugged the opti in and everything was fine.
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Old 09-12-2011, 09:55 PM
  #20  
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Re: Please help lt1 wont start

well thans for the advice... tolday i bought a obd1 scanner and im gonna try it.. also if the injector pulse was wrong what could be causing that?....
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Old 09-13-2011, 05:21 AM
  #21  
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Re: Please help lt1 wont start

If you are asking about Psycho's point #3, he's is suggesting that you use a 'noid light to verify that the injectors are firing (pulsing). If they don't pulse, the engine doesn't get fuel. The injectors always have 12V supplied to them. The PCM provides a ground to fire them. If you have a problem with the injector circuits, you would have code DTC 18. Additionally, there are other fault codes that cause the PCM to shut down the injectors. DTC 16 is a typical example.
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Old 09-13-2011, 04:37 PM
  #22  
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Re: Please help lt1 wont start

This happened to me once in my work truck. driving along as usual and the truck just turned off at like 50mph. Turned out the fuel pump went out. Just a thought
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Old 09-14-2011, 11:59 PM
  #23  
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Re: Please help lt1 wont start

whats a good obd1 scanner?.... any recomendations?
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Old 09-15-2011, 12:05 AM
  #24  
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Re: Please help lt1 wont start

auto xray ez-scan 3000. I've had one for several years and its been great.

Edit: also for 95's, you can pick up the specific cable as part # 20211
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