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  • Pro Flo Won’t Start

    358600 Flo Pro 4 kit

    540bbc Chevelle
    AFR 305 Heads
    New moroso ultra 40 8.65 mm spark plug wires
    New Champion copper plus plugs, gapped 0.035”
    New 1000 CCA Battery
    7AL2 Ignition
    HVC 2 Coil

    The engine sputters but does not start. I have double checked timing and all connectors. I have made sure I have adequate spacing between spark plug wiring and distributor signal to avoid EMI issues. I did have fuel and throttle position hooked up backwards (initially)- hope that didn’t cause any issues.

    I noticed vacuum is about -2.5” HG during cranking, which seems low. Maybe that’s right, because the car would idle with a carb at about 8”. Without cranking, the MAP sensor reads -0.6” HG. The difference in fuel pressure is about 1.8psi when cranking vs not, which is the same as about 3.6” HG, so it’s possible the map sensor is reading wrong?

    On the diagnostic screen, “ignition voltage” shows red immediately when I start cranking. What voltage is this reading? Is this the voltage on the “coil +” wire going to the 7AL2 “ignition” terminal?

    Should I have switched 12V power going to same termination as the “coil +” wire from the wiring harness? The 7AL2 manual shows it wired liked this for an ingition control module set up with regular distributor points. Right now I just have the “coil +” wiring going to “ignition” and the “coil -“ wire (white) going to “points” on the 7AL2.

    Attached is a screenshot during cranking. Any help is hugely appreciated, I’ve been stuck trying to figure this out for a few days now!

    Before Cranking:
    image_3582.jpg

    During Cranking:
    You do not have permission to view this gallery.
    This gallery has 2 photos.
    Last edited by Theron; 04-12-2021, 07:56 AM.

  • #2
    Also: MAP reads -0.6in HG when not cranking. So it had an offfset for some reason.

    Comment


    • #3
      If that screen shot is during cranking, it's not showing any RPM's, which means the coil is not firing. Bypass the MSD system and see if it will crank. Make sure the pink/black ignition wire is getting 12 volts while cranking. You might want to put a temporary wire and switch directly to the battery. And we're going to assume the positive and negative wires are going directly to the battery, not on any other circuit?

      Comment


      • #4
        Originally posted by CorkyE View Post
        If that screen shot is during cranking, it's not showing any RPM's, which means the coil is not firing. Bypass the MSD system and see if it will crank. Make sure the pink/black ignition wire is getting 12 volts while cranking. You might want to put a temporary wire and switch directly to the battery. And we're going to assume the positive and negative wires are going directly to the battery, not on any other circuit?
        The image function of this forum is not so good. I think I fixed them. There are two images. The second one is during cranking. Cranking RPM with no fire is about 150rpm. With a sputter, it hits like 300rpm.

        Comment


        • #5
          Sounds like the PINK/BLACK is not getting a "uninterrupted" Ign/Crank signal.
          Use a toggle switch on it. With it connected to the battery positive.
          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.
          https://forums.edelbrock.com/filedat...?photoid=42773

          Comment


          • #6
            Originally posted by BITE_ME View Post
            Sounds like the PINK/BLACK is not getting a "uninterrupted" Ign/Crank signal.
            Use a toggle switch on it. With it connected to the battery positive.
            I suspect you are right. I also wonder if the connection I’m using actually cuts power. I know my gauges cut power when cranking, so if I came off of the same block, then i could have zero power on this terminal when cranking. I’ll check and report back.

            Do you know the minimum voltage that must be available to this pink/black cable? If voltage is sufficient, can it handle voltage fluctuation? I see quite a voltage drop when this thing cranks, but probably because I’ve been cycling it so much (hope it resolves once each crank leads to a start in the future).

            Comment


            • #7
              Originally posted by Theron View Post

              I suspect you are right. I also wonder if the connection I’m using actually cuts power. I know my gauges cut power when cranking, so if I came off of the same block, then i could have zero power on this terminal when cranking. I’ll check and report back.

              Do you know the minimum voltage that must be available to this pink/black cable? If voltage is sufficient, can it handle voltage fluctuation? I see quite a voltage drop when this thing cranks, but probably because I’ve been cycling it so much (hope it resolves once each crank leads to a start in the future).

              Pink/Black wire needs Constant 12v power, during run/crank positions.

              PF4 doesnt like voltage drops, Like was recommended Jumper the Pink/black straight to battery with a toggle for testing.
              Don't get too caught up in the numbers.
              Just give the Engine what it wants &
              Let the numbers be what they are.

              Jim McFarland....

              Comment


              • #8
                Ok, hooked pink/black straight to battery with toggle switch. Exact same symptoms. Here is another screenshot during cranking.

                Attached Files
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                This gallery has 1 photos.

                Comment


                • #9
                  Do you all think that overall system voltage drop during cranking is too high? If so, what would cause this? Battery is brand new. Maybe starter cables or something? Or starter is undersized or going bad.

                  Comment


                  • #10
                    Battery voltage drop is common during starting, 11.4 isn't that terrible. What map are you using, and have you tried taking the MSD out of the equation?

                    Comment


                    • #11
                      Originally posted by CorkyE View Post
                      Battery voltage drop is common during starting, 11.4 isn't that terrible. What map are you using, and have you tried taking the MSD out of the equation?
                      Note: if you take the MSD out of the loop...that HVC coil will damage the ECU.
                      You can use a MSD #8202 blaster2 in its place.

                      Have you checked for spark at the plugs? Will it run with a shot glass of fuel down the intake ?

                      Note: 50 RPM on tablet seems slow-----normally 135-150 ish----check battery/starter/cables , etc.

                      Recheck the short tooth : https://forums.edelbrock.com/forum/p...on-timing-sync


                      What engine?
                      Vehicle make & model?
                      What MAP # is it on?
                      Fuel pressure ?
                      Hot engine idle vacuum?
                      Injector size ?
                      HP level ?
                      Spark control settings ?
                      Last edited by 2700 Cast; 04-13-2021, 08:33 AM.
                      Don't get too caught up in the numbers.
                      Just give the Engine what it wants &
                      Let the numbers be what they are.

                      Jim McFarland....

                      Comment


                      • #12
                        Originally posted by CorkyE View Post
                        Battery voltage drop is common during starting, 11.4 isn't that terrible. What map are you using, and have you tried taking the MSD out of the equation?
                        i have not tried to take the MSD out if the equations, because I didn’t want to damage the coil or vice versa.. i hear you though, and will cross this road if I need to.

                        Comment


                        • #13
                          Originally posted by 2700 Cast View Post

                          Note: if you take the MSD out of the loop...that HVC coil will damage the ECU.
                          You can use a MSD #8202 blaster2 in its place.

                          Have you checked for spark at the plugs? Will it run with a shot glass of fuel down the intake ?

                          Note: 50 RPM on tablet seems slow-----normally 135-150 ish----check battery/starter/cables , etc.

                          Recheck the short tooth : https://forums.edelbrock.com/forum/p...on-timing-sync


                          What engine?
                          Vehicle make & model?
                          What MAP # is it on?
                          Fuel pressure ?
                          Hot engine idle vacuum?
                          Injector size ?
                          HP level ?
                          Spark control settings ?
                          I haven’t checked all wires for spark. Will do.

                          i have not put fuel down the intake either. Will give this a try.

                          i have double checked the short tooth twice. In fact using the document you recommend. This should be pet of the instructions, as it was a god send LOL.

                          540bbc low deck bowtie
                          1970 chevelle Malibu
                          cal id 5039
                          hot engine vacuum is 6-8” HG on carb
                          60lb/hr injectors
                          engine is expected to have about 700 on the motor
                          i have spark control set at 10.50 adv, because this gives me the best sputter that almost seems like it wants to start. I have also tried locked timing of course.

                          what do you think?






                          Comment


                          • #14
                            Spark control > idle spark = 23 degrees ( per your big cam )

                            What do you mean " tried locked timing " ??
                            Don't get too caught up in the numbers.
                            Just give the Engine what it wants &
                            Let the numbers be what they are.

                            Jim McFarland....

                            Comment


                            • #15
                              Originally posted by 2700 Cast View Post
                              Spark control > idle spark = 23 degrees ( per your big cam )

                              What do you mean " tried locked timing " ??
                              Wow, good point. I was following the directions a bit too literally since I cannot figure out what’s wrong. I’ll play with advancing the timing. In doing so, I definitely get better response when the car tries to fire, but it still doesn’t start. I think the suggestion help, but I guess it’s not my root cause.

                              Not sure if I mentioned but this is a new installation. By locking the timing, I only mean that I’ve tried the start up wizard.

                              I also noticed the car is running lean at start, so added a lot of fuel. Seems to help, but not enough.

                              Tomorrow, I’ll look at adding fuel to the intake, and then finding a better way to verify spark. I think it’s odd to see the engine periodically hit “0” rpm during cranking, as someone pointed out prior.

                              I’m on turnaround at work at the moment. Here’s the latest screenshot during cranking: A9A9D833-323E-46E9-8AC2-2054C3EF1725.jpeg

                              Comment

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