No injector Pulse

Tiny
MEXIKEE
  • MEMBER
  • 2001 GMC SONOMA
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 15,000 MILES
Engine cranks fine, has spark, has 55 lbs. Fuel pressure. All fuses good. Engine runs when fuel added to throttle body. Suspect bad ECM. Help me, I need my truck!
Sunday, April 12th, 2020 AT 2:34 PM

4 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening,

Yes, if it runs on fuel then the injectors are not being pulsed.

I attached a picture of the ECM and a wiring diagram of just the injectors.

Roy
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Sunday, April 12th, 2020 AT 3:44 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I agree with Roy. However, the only thing you need to check first would be a security lock out. On this truck the BCM and PCM will cut the fuel injectors if there is a security issue. However, the last line in the attachment should be the telltale if this is the issue.

If the vehicle starts then stalls it is a security issue. I thought it important that we make that distinction. Thanks
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Sunday, April 12th, 2020 AT 4:31 PM
Tiny
MEXIKEE
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Thanks guys for the intel. It's greatly appreciated. As far as the lock out goes, I got online and found a site that details how to reset it. See if you guys agree, first you crank the engine, leave key in run position, wait 10 minutes, security light should stop flashing and go out. Turn key off, wait 5 seconds and repeat process at 3, 10 minute cycles. I did all that but my concern is the security light doesn't flash, it turns on and goes out as it should normally. That leads me to believe that there really isn't an issue with the lock out. It didn't work by the way. Please let me know what your thoughts are about that. Meanwhile. I'm going to assume that we all agree my ECM is shot. Let me know and again I sincerely appreciate your help.
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Monday, April 13th, 2020 AT 3:18 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
If the light comes on and goes off, that is not the issue. It is working normally.

Did you verify the wiring to the ECM? If the wiring is good, then yes, the ECM is the issue.

Roy
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Monday, April 13th, 2020 AT 3:25 PM

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