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Thread: Holley Commander 950 Pro - Fuel primes, but no fuel when cranking.

  1. #1

    Default Holley Commander 950 Pro - Fuel primes, but no fuel when cranking.

    Hello. I recently picked up a 1995 Chevy S10 with a built 4.3L V6. I'm trying to get it up & running again, but I'm having some trouble. A few months ago, I went through all the wiring and figured out what's what and got it going, but now I don't have fuel while the engine is cranking over. When I turn the key to the ON position, the injectors prime for 5 seconds. When I turn the key to crank it over, no fuel comes from the injectors. I think I may have a loose wire somewhere, but I'm not exactly sure what I'm looking for, and don't fully understand the whole system. Any help would be greatly appreciated. Thank you.

    EDIT: I should also mention that the truck has an MSD 6AL box as well as an MSD distributor, and an Accel coil. -Alex
    Last edited by murfx2004; 05-22-2016 at 07:26 PM.

  2. #2
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    Quote Originally Posted by murfx2004 View Post
    When I turn the key to crank it over, no fuel comes from the injectors.
    When cranking to start, is the "Fuel Pump On" indicator highlighted red (Fuel & Spark Map)?
    If not, the ECU isn't receiving an RPM signal from the CD ignition box.
    http://documents.holley.com/techlibrary_r10149-7.pdf (Holley Commander 950 Pro Manual - Figure 82, Page 107)

    ...and don't fully understand the whole system. Any help would be greatly appreciated.
    http://documents.holley.com/techlibrary_r10149-7.pdf (Holley Commander 950 Pro Manual)

    EDIT: I should also mention that the truck has an MSD 6AL box as well as an MSD distributor, and an Accel coil.
    Is this an ECU timing control application? If so, which part number MSD distributor?

    Testing the MSD CD ignition box.
    Points Output - white wire & Magnetic Pickup - violet/green triggering:
    https://www.msdperformance.com/suppo...ng_techniques/ (Troubleshooting Info)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Thanks for the response, Danny. I don't have the cable to connect the unit to the computer or the software to run it. I picked the truck up non-running with many parts in boxes, but unfortunately I do not have those. Would there possibly be another way to check without using the computer? I'll have to check up on the MSD distributor part number in the daylight. Thank you again.

    EDIT: I do have spark, so I know that the MSD is functioning in respect to supplying current to the plugs.
    Last edited by murfx2004; 05-24-2016 at 09:24 PM.

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    Quote Originally Posted by murfx2004 View Post
    I don't have the cable to connect the unit to the computer or the software to run it.
    You can download the Commander 950 Pro EFI software here:
    https://www.holley.com/support/resou...Fuel_Injection (Scroll down to "Commander 950 Software".)
    And the Commander 950 Pro EFI communication cable is available here:
    https://www.holley.com/products/fuel.../parts/534-140 (C950 Communication Cable)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

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    Thank you for the links. The part number for the MSD distributor is MSD 8597. Also, I just discovered the communication cable was neatly tucked away underneath the floor mat, deep in the foot well. I will download the software and give this a shot over the weekend, and post my results.

  6. #6
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    Quote Originally Posted by murfx2004 View Post
    The part number for the MSD distributor is MSD 8597.
    So this is not an ECU timing control application?
    http://documents.holley.com/techlibrary_r10149-7.pdf (Holley Commander 950 Pro Manual - Figure 82, Page 107)

    Excerpt from Holley EFI manual:
    NOTE - It is not advised to use a magnetic pickup distributor to directly feed the magnetic trigger input of the ECU. If the
    magnetic pickup distributor is connected to the ECU via the inductive pickup trigger wires, the pickup/rotor/cap phasing
    must be corrected. This operation may require a phaseable cap or rotor or possibly machining to the distributor and is
    therefore beyond the scope of most users. Even with the phasing corrected, the electrical noise inside the cap
    (due to the high voltage cap & rotor terminals) may be strong enough to cause electrical noise interference.
    It is advised to use a crank trigger system or a computer-controlled distributor.

    I will download the software and give this a shot over the weekend, and post my results.
    When cranking to start, is the "Fuel Pump On" indicator highlighted red (Fuel & Spark Map)?
    If not, the ECU isn't receiving an RPM signal from the CD ignition box.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #7

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    Here's what I've gathered. I tested the MSD ignition following the directions in the link and it's functioning properly. I cranked it with the laptop hooked up, and the Fuel Pump Indicator is highlighted in red. So something is not telling the injectors to fire when it's cranking. I'm not sure where to go from here.

    EDIT: After messing around with it a little bit more, it started to spray fuel while cranking. I connected a dangling ground wire, which made it go, but then it still sprayed even when I disconnected it again. Then, oddly enough, it would no longer spray fuel when priming. The fuel pump hums, but the injectors do not spray for whatever reason.
    Last edited by murfx2004; 05-27-2016 at 08:46 PM.

  8. #8
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    Quote Originally Posted by murfx2004 View Post
    I connected a dangling ground wire, which made it go, but then it still sprayed even when I disconnected it again.
    Please ensure the EFI system is correctly installed, before we troubleshoot a problem.

    Then, oddly enough, it would no longer spray fuel when priming. The fuel pump hums, but the injectors do not spray for whatever reason.
    I would troubleshoot the system relay. It may be defective or have corroded terminals.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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