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Promac questions

Discussion in 'Generators/Gensets' started by lmm600, Jan 27, 2021.

  1. Birken Vogt

    Birken Vogt Charter Member

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    I was working on a Kubota recently that had its RPM sensor up on the cam gear or something. It was one of those non-adjustable plastic sensors with a tab with 1 bolt off to the side, and 3 wires to it so it was some kind of active sensor that takes power to work. So it could be elsewhere on the engine than the starter gear.
     
  2. MarshallPowerGen

    MarshallPowerGen Well-Known Member

    Joined:
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    Occupation:
    Diesel & Generator Mechanic
    Location:
    Coeur d'Alene, Idaho
    If the controller reads off of frequency, it would not be from a sensor. It would be AC leads from the generator output to the controller, and be reading frequency from the generator AC output.

    Your controller is either going to read RPM through output HZ, an engine speed sensor (flywheel/crank/cam), or the engine alternator hz.
     
    mg2361 likes this.
  3. Midnightmoon

    Midnightmoon Senior Member

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    Trace wire back to its origin. There is probably a few connections from input to controller. Maybe just a bad connection. You'll also find the pick up
     
    MarshallPowerGen likes this.
  4. Midnightmoon

    Midnightmoon Senior Member

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    One thing to check that I have come across. Make sure there is a diode on starter solenoid between the 2 small lugs. Also alternator needs one on excitter wire. Not sure if yours is set up that way without a wire diagram but many generators are. If there isn't a diode or diode is bad it will cause issues at controller. There are diodes on relays as well that are external to the relay.
     
  5. lmm600

    lmm600 Active Member

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    Idaho
    I'm finding out the alternators aren't a common unit. They have a pig tail hook up that has a diode and resistor. One of these has a broken resistor and I've had three different shops just say sorry but.....
    I have another shop that I'm going to try this afternoon (they say they can check all components), only about 50 miles away.
    Then its back to a heck of a lot of wire tracing/checking.
     
  6. Midnightmoon

    Midnightmoon Senior Member

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    I just finished up a second generator that the customer changed the alternator and it didnt charge afterwards. All you need is a diode from napa and a mini fuse holder
     
    lmm600 likes this.
  7. lmm600

    lmm600 Active Member

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    Just an update. Got two generators that appear to be operating correctly (key word appear).
    Third one is really aggravating. At first it would go into its start sequence and engine would turn over but not start (rpmmeasfail). After doing some testing and checking now it does nothing. Controller says its going thru its sequence but nothing happens at fuel solenoid, lift pump, starter.
    Also, Marshall: Robert from Selkirk Power has spoken with me a few times but always cancels when he says he can look at them. Another fellow from Rathdrum really wants to shy away when I mention Pramac.
     
  8. MarshallPowerGen

    MarshallPowerGen Well-Known Member

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    Occupation:
    Diesel & Generator Mechanic
    Location:
    Coeur d'Alene, Idaho
    So after checking a few things it's not doing anything? That sounds like a wiring issue, and I'd be verifying the signal voltage for the different components coming from the controller and where they end up. Glad to hear the other two appear to be operating correctly, and might be good to use as a reference for how your problem child is wired.

    I spoke with Robert last weekend, didn't realize his primary field guy left a month or so ago, so he's operating solo and overwhelmed at the moment. Most of the folks doing generator work in this region don't seem to be interested in doing more than an oil change or selling a replacement. Troubleshooting takes time, and on an oddball machine without documentation or parts readily available can end up being a big loss that can't realistically get billed for.
     
    lmm600 likes this.