1988 GMC C1500 No Start

Tiny
CARLYLE 1
  • MEMBER
  • 1988 GMC C1500
Engine Performance problem
1988 GMC C1500 6 cyl Two Wheel Drive Automatic

I have 1988 Gmc with a 4.3 L engine will not start new plugs, wires, cap and rotor, and module. Has no spark, and no fuel at the injectors but there is power to the injectors. It has throttle body injection. Fuel in the lines when turning over but will not start was running before. And runs smooth when running just a matter of getting it started.
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Saturday, November 14th, 2009 AT 8:35 PM

5 Replies

Tiny
JDL
  • EXPERT
Welcome to the forum, Is the coil in the cap? If so check B+ terminal at the cap for voltage, pink wire, goes hot when you turn on the key. There is probably a tach terminal next to it, use a testlite on that terminal, the lite should pulse.

The purple wire with white tracer, goes from the distributor to pcm, carries rpm signal, engine cranking, there is a pulse on that circuit, without that signal, no injector pulse, the pcm controls injector ground.

With the bypass ignition system, during cranking, the computer doesn't control spark timing, the ignition module does. If everything else checks out, check the pickup coil. Also, are there any trouble codes?
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Sunday, November 15th, 2009 AT 10:47 AM
Tiny
CARLYLE 1
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The coil is seperate but should be same set up right?
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Sunday, November 15th, 2009 AT 11:35 AM
Tiny
JDL
  • EXPERT
Yes, B+ and negative side of coil, goes hot with the key on. With testlite on negative side, the lite should pulse, engine cranking. If no pulse, the ground isn't being switched for some reason.
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Sunday, November 15th, 2009 AT 11:54 AM
Tiny
CARLYLE 1
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Hooked up test lead to rpm lead off coil it lights up but does not flash when cranking. The purple one does not either on the distributor. I don't have a scan tool, but I am sure ther is antoher way I can read the codes by useing a jumper wire
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Wednesday, November 18th, 2009 AT 6:23 PM
Tiny
JDL
  • EXPERT
You may not be able to use a testlite on the purple wire? If you have dmm with a tach setting, that should give reading? Right now, my thought is something wrong with the pick-up coil. I have heard of using flashlite battery, 1.5 volt, to trick the ignition module into thinking it is receiving a signal from the pickup coil, with the key on, it may cause a spark. Don't get bit by secondary ignition voltage, it never hurt me,but, always surprises me. I don't like it.

Yes, you can check codes using a jumper wire.


http://www.2carpros.com/forum/automotive_pictures/170934_aldl_35.jpg

, you place jumper between terminals A & B, turn the key on, no crank. The check engine lite starts flashing, you count the flashes to get the codes, two digit codes. A code 12 is one flash, slight pause, two quick flashes. It may repeat code three times before moving to the next code, if there are any?
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Thursday, November 19th, 2009 AT 8:22 AM

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