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  • ECU sudden death??

    Edit!!!! "SOLVED!!"

    So I have run my PF4 for one year without one single problem....Its been great until today!
    The engine went from perfect running to almost a sudden death....It just died without any warnings and needed to tow the car.

    It will not try to start either when running the starter...Just some random "poff" ....No backfiring.

    So I started to check everything and this is what I have checked
    - Fuel pressure OK...Fills a cup within a couple of second
    - Spark OK when cranking
    - Pink wire get 12V
    - Coil OK! I measured both primary and secondary fields
    - When key in IGN coil gets 0 volts! Shouldn't it be 12V?
    - MSD 6AL diod "flickers" when cranking
    - All wires and connections OK (soldered where needed)
    - Distributor rotor OK and turning

    My first guess was something in the MSD 6AL but I am not sure now
    It almost feels like the injectors are not firing.

    My fear is something just happened to the ECU!!

    How can I go further with the diagnostic?

    Here is a clip of the system when cranking.....Note fuel pump disconnected in clip!
    Looks like a mess but I loosen everything for checking wires.

    Last edited by PerBerglund; 08-18-2020, 01:58 PM.

  • #2
    Remove the MSD from the equation and run the coil by itself. Looks like your sensors are working. If your fuel pressure is normal then I'd look at the MSD. My MSD died too.

    Be sure to check you have 12v at the coil.
    Last edited by K5shawn; 08-07-2020, 11:03 AM.

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    • #3
      Originally posted by K5shawn View Post
      Remove the MSD from the equation and run the coil by itself. Looks like your sensors are working. If your fuel pressure is normal then I'd look at the MSD. My MSD died too.

      Be sure to check you have 12v at the coil.
      Thanks man!

      I checked the manual and it says use harness "#37-1634" if running without CDI box
      #37-1634 is some sort of "coil driver"?

      Or just just wires directly to coil?

      Screen Shot 08-07-20.JPG

      Would not surprise me if MSD died! I sold my old 1994 analog MSD6A and put in a new Digital....Heard they are not as dependable!
      Last edited by PerBerglund; 08-07-2020, 11:58 AM.

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      • #4
        did you check for spark from the coil ? then at the spark plugs and see a bright blue spark ? use a spark tester. if the m s d hits you it could put you on the ground or death i.e stop your hart. BE SAFE

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        • #5
          Originally posted by fleet man View Post
          did you check for spark from the coil ? then at the spark plugs and see a bright blue spark ? use a spark tester. if the m s d hits you it could put you on the ground or death i.e stop your hart. BE SAFE
          I just double checked it.....This clip wire directly from coil
          It looks fine to me! So MSD might be OK

          Comment


          • #6
            Pour a shot glass of fuel down the t-body...

            Does it light off/cough?

            Verify fuel psi with a manual gauge.

            Comment


            • #7
              Originally posted by 2700 Cast View Post
              Pour a shot glass of fuel down the t-body...

              Does it light off/cough?

              Verify fuel psi with a manual gauge.

              The external fuelregulator has a gauge and shows about 60psi

              I pulled the fuse for the fuel pump and tested as you advised and now the engine goes!!


              Comment


              • #8
                So it's fixed? If the engine starts then definitely not your MSD.

                When I removed my MSD CDI, I connected the Orange wire goes to the positive (+) terminal and the White wire goes to the
                negative (-) terminal on the coil. Haven't went back to CDI since.

                Comment


                • #9
                  Originally posted by K5shawn View Post
                  So it's fixed? If the engine starts then definitely not your MSD.

                  When I removed my MSD CDI, I connected the Orange wire goes to the positive (+) terminal and the White wire goes to the
                  negative (-) terminal on the coil. Haven't went back to CDI since.
                  No its not fixed.
                  But you are correct the MSD works

                  In the clip the fuel pump is disconnected so the engine only gets fuel from the bottle I pour from

                  If i connect the fuel pump again nothing happens....Not even trying to start

                  My guess is that the injectors do not get a firing signal....... Or can the sensor for injector firing in the distributor go bad?
                  As I understand the distributor has 2 sensors....1 for ignition and the other for fuel injection?

                  Any other ideas?
                  Last edited by PerBerglund; 08-07-2020, 02:38 PM.

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                  • #10
                    Test your o2 sensor.

                    Comment


                    • #11
                      https://www.youtube.com/watch?v=Xsr55FInfwk

                      Comment


                      • #12
                        you need a noid light to plug into 1 of the injector connector and see if it blinks like a spark plug.

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                        • #13
                          Originally posted by fleet man View Post
                          you need a noid light to plug into 1 of the injector connector and see if it blinks like a spark plug.
                          This.
                          Because your not getting fuel.
                          In my neighborhood, if you open your hood to check your oil, and the vehicle still runs after you close it.......Then your labeled the Neighborhood Mechanic.

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                          • #14
                            See if your injectors are getting 12v. One side should be steady 12v. The other side is switched ground from the injector drivers in the ECU. You may have to measure this while its cranking. Many ECUs keep the injectors hot as long as the fuel pump is hot. But this ECU may differ.

                            Comment


                            • #15
                              As tested the engine do not get fuel from the injectors so why bother to measure the Volts in the injectors?
                              The do not open and all 8 can't get a mechanical or wiring problem all at the same second......I have checked all wiring
                              This fault happened like you would flick of a switch....I was cruising around in 30mph and the engine just shut of .....
                              So it feels like some kind of electronic/communication fault.

                              O2 sensor is OK since the readings are OK and I doubt a O2 sensor would kill the fuel in this way.


                              I will do some more testing tomorrow.
                              Is there anything I can test on the ECU?

                              Comment

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