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Old 06-28-2010, 11:15 AM
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Helping a friend with an intermittent no start

Helping a friend with an intermittent no start no spark has fuel? 1989 Chevy P/U 350. He already put in a new distributor module, cap rotor plug wires, coil, ecm. Would anyone have a wiring diagram for this trucks ecm or distributor. Thank you for your time...JOHN

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Old 06-28-2010, 11:42 AM
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This engine ever been rebuilt? Have all the grounds been gone over and tighten down? It could be that simple. Run a new ground jumper from the battery (-) terminal to the engine using multi-strand 12 gauge wire and see if it cranks over first time.
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Old 06-28-2010, 11:53 AM
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Originally Posted by alittle1
This engine ever been rebuilt? Have all the grounds been gone over and tighten down? It could be that simple. Run a new ground jumper from the battery (-) terminal to the engine using multi-strand 12 gauge wire and see if it cranks over first time.
No original eng no rebuild. Had him ck and clean all grounds he could find.. body and eng. Thatís the reason I need a wiring diagram to see if there's more under the dash or hiding somewhere
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Old 06-28-2010, 01:10 PM
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Is there an injector pulse?
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Old 06-28-2010, 01:36 PM
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Originally Posted by ethn_bert
Is there an injector pulse?
frome what he tells me yes...
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Old 06-28-2010, 02:14 PM
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No spark, but injector pulse means faulty coil or related wiring; power feed wire or coil(-). There won't be injector pulse if there was a bad ignition module(most cases). You could have a weak pickup coil.
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Old 06-28-2010, 02:55 PM
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Quote:
Originally Posted by ethn_bert
No spark, but injector pulse means faulty coil or related wiring; power feed wire or coil(-). There won't be injector pulse if there was a bad ignition module(most cases). You could have a weak pickup coil.
power feed wire. would you know if thers a relay that would feed the coil under the dash ?
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Old 06-28-2010, 05:33 PM
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No relay. The ignition coil is fed power(pink wire) directly from the ignition switch. During cranking(until 400rpm) the ECM doesn't apply the 5volts on the bypass circuit and the base timing curce in the module controls the spark operation. If there is no spark from the coil, but there is an injector pulse then Therefore, the ecm is recieving the crank/timing signal on the high reference line and is pulsing/working correctly. So, it has to be a wiring issue, faulty coil, or pickup coil dropping in and out(their would be random spark and injector pulse). Don't forget you secondary ignition system! That is why it is very important that you are sure that the injectors are pulsing. Also, for future reference, that ignition system will/should spark without an ECM connected(until about 400 rpm) and therefore an ECM is highly unlikely to cause a no start with no spark issue. I said highly unlikely because obviously internal shorts on the bypass and reference cicuits inside the ecm will cause a no start.
Good Luck.
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Old 06-28-2010, 06:50 PM
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Quote:
Originally Posted by ethn_bert
No relay. The ignition coil is fed power(pink wire) directly from the ignition switch. During cranking(until 400rpm) the ECM doesn't apply the 5volts on the bypass circuit and the base timing curce in the module controls the spark operation. If there is no spark from the coil, but there is an injector pulse then Therefore, the ecm is recieving the crank/timing signal on the high reference line and is pulsing/working correctly. So, it has to be a wiring issue, faulty coil, or pickup coil dropping in and out(their would be random spark and injector pulse). Don't forget you secondary ignition system! That is why it is very important that you are sure that the injectors are pulsing. Also, for future reference, that ignition system will/should spark without an ECM connected(until about 400 rpm) and therefore an ECM is highly unlikely to cause a no start with no spark issue. I said highly unlikely because obviously internal shorts on the bypass and reference cicuits inside the ecm will cause a no start.
Good Luck.
Sounds good i'll pass on the info thank you...
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