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  1. #16
    Very strange starting TedC's Avatar
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    EEvette, Now we are getting somewhere. :-) I'm hoping those with more knowledge on the L98 ignition will speak up. My 1989 has no issue jumping the gap during cranking all the way up to 40 using a similar tool. I think the 40 setting represents 40,000 volts, and the stock L98 coil can produce some really high voltages.

  2. #17
    EEvette
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    TedC, I wonder if its ignition related. Like I said, once the engine started the spark would jump the 40 gap inconsistently.....when I reduced the distance to about 20 I would get consistent sparks.

    Anyone that knows more about this please speak up.

  3. #18
    Very strange starting TedC's Avatar
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    EEvette, I would think a spark strong enough to reach 20 should be enough to ignite the fuel. If I understood your prior post, you did not see any spark of any quality during crank. Please confirm the long start when engine is both cold and hot.

    Some addition info on pre 1989 L98s...
    WHAT THE ECM - PCM DOES: The 1985-1988 TPI system utilizes the following sensors and devices to control the engine: Mass Air Flow Sensor, Manifold Air Temperature, Coolant Temperature, Oxygen Sensor, Throttle Position Sensor, Cold Start Switch, Cold Start Injector Fuel Injectors, Idle Air Control Valve, Distributor Electric Spark Timing, (Module in distributor TPI) Electric Spark Control, Module and Knock Sensor.

    When the starter is engaged and the coolant temperature is less than 100 deg F. The cold start injector provides a spray of fuel, of 8 seconds duration max, to each cylinder via a air distribution system built into the intake manifold. If the engine temperature is greater than 100 deg F, the cold start injector is disabled by the cold start switch. Upon startup the ECM utilizes information in the calibrator to establish the initial pulse rate for the injectors and the engine starts. At this time the engine is operating in open loop mode and will continue to do so until the engine warms up. After the warm up period the ECM scans the sensors, if all sensors are operating and within their proper range, the engine then goes into closed loop operation.

  4. #19
    EEvette
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    tedC,

    Here are a few things I have noticed:

    Starts cold with no problems.

    After being driven, lets say I go to the store and I come back to start it, takes a while 5 to six seconds. If I turn it off once it starts (hot) and immediately turn the key, it starts. I guess it has to sit for a while after being driven for the problem to surface.

    With the gap set at 40, no spark during cranking (hot) on cylinder 1 but engine eventually started.

    Once started spark would not jump 40 gap.

    I guess I need to check fuel pressure to see if there is any loss from the time I turn the key, to maybe ten minutes after in the off position. I will do that as soon as I get home.

  5. #20
    Very strange starting TedC's Avatar
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    EEvette, The results of the pressure test are key. My 1988 would not start right away after sitting hot for 5-20 minutes. Had to crank for 5+ seconds. It would start fine hot if started right after shut off or I waited a few hours. Leaking injectors can cause a rich condition that requires the extra cranking to clear the combustion chambers. What I don't understand is why you are not seeing any spark during this situation.

  6. #21
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    TedC,

    I will go test fuel pressure and run another spark test...perhaps try another cylinder and reducing the gap. I will post results later this afternoon. Thanks for all the help, greatly appreciated.

  7. #22
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    Ok, Just finished doing th fuel pressure tests, I found the following:

    Turn key to on position: pressure reaches 42 psi then immediately drops to 0

    Turn car on: fuel holds a steady 41-42 psi

    Turn car off: pressure immediately drops to 0

  8. #23
    Very strange starting TedC's Avatar
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    EEvette, I copied this from another post... Pressure should not drop like that...

    "There is a check valve on the tank pump assembly that holds pressure This may be bad or your regulator may not be holding pressure or possibly a bad injector bleeding off pressure."

  9. #24
    Very strange starting TedC's Avatar
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    EEvette, Here is what the 1989 FSM states...
    Pressure that continues to fall is caused by one of the following:
    1. Fuel pump check valve not holding (in the tank)
    2. Pump coupling hose or pulsator leaking
    3. Fuel pump regulator valve leaking
    4. Injector(s) sticking open
    With the ignition on, fuel pump runs for 2 seconds. Pressure builds and should hold steady when pump stops.

  10. #25
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    TedC,

    Thanks for your help. I removed (tried) the fuel rail last night to check the fuel injectors for leaks. I encountered a small problem, one of the torx screws that holds the cross pipe broke when unscrewing, it might have seized in place. I am sure I can remove whats left in there but the problem is where can I get another one of those screws? Any ideas?

  11. #26
    Very strange starting TedC's Avatar
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    Chevy dealer or auto parts store???

  12. #27
    EEvette
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    Im gonna visit the chevy dealer hopefully they have something. Thanks TedC.

    As far as the troubleshooting goes, I will keep you posted I know someone has the same problem. It might take me some time as I just got assigned a big project at work that will leave little spare time to work on my car......but like I said I will post as soon as I find something.

    Once again thanks for all the help.

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