1989 Chevy Camaro tbi not pulsing

Tiny
BIGGD4355
  • MEMBER
  • 1989 CHEVROLET CAMARO
  • V8
  • 2WD
  • AUTOMATIC
  • 145,000 MILES
I have constant power to my injectors but have no grounding pulse from the ecm. The color codes from my hanes book don't match the ecm.I replaced the icm about a month ago. The car just died at a stop sign. No spark and no fuel. The new icm fixed the spark problem. I also replaced the ecm a month ago. Any ideas what would cause the icm to go out and the pulse problem for the injector problem?
Saturday, September 4th, 2010 AT 6:28 PM

3 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Right now, you do have spark at the plugs? Any applicable trouble codes? If the computer doesn't see an rpm signal, there won't be an injector pulse. The purple wire with white tracer carries the rpm signal from ignition module to computer, no signal no injector pulse.

For distributor, the rpm signal comes from the pickup coil to ignition module to computer. If there was a problem that caused the old ecm to go bad, if you didn't fix it, it may cause problems with the new ecm?
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Sunday, September 5th, 2010 AT 2:21 PM
Tiny
BIGGD4355
  • MEMBER
  • 4 POSTS
To JDL, I have excellent spark to the plugs. I can put a little gas in the throttle body and it will run til that fuel is gone.I just had the new icm tested and it tested good.I have continuity from the icm to the ecm but no pulse. If the distributer was bad I wouldn't have spark. Can it be a bad second ecm?
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Sunday, September 5th, 2010 AT 3:24 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Any applicable trouble codes? You have 2.8L? Do an ohms test on injector/s.

If you have a digital multimeter that has a tach--duty cycle or dwell setting any of those settings should react to a dc pulse. Check the purple wire with white tracer, engine cranking. My info says the voltage is around 1.6 volts, you should look for a pulse.

I haven't had good experiences with autostore testing parts. I probably only remember the times they were wrong?
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Monday, September 6th, 2010 AT 10:19 AM

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