Older Scag Zero with two problems

Discussion in 'Mechanic and Repair' started by trailboss, Sep 20, 2009.

  1. trailboss

    trailboss LawnSite Member
    Messages: 206

    It is an older Scag Zero that has had the Kohler motor replaced about six years ago. Ive looked all over the thing (motor) and cant find any model#. It had a problem for a while that seemed like an ignition problem - sometimes you would turn the key and get nothing then sometimes it would fire right up. A few days ago it stopped all together - turn the key and totally dead. I thought that it might be the ignition switch - put a new one in and new relay and new battery - turn the key and get nothing. I can turn the key/switch to the on position and run a wire straight from the battery to the small terminal on the solenoid and it fires up. I have checked and cleaned connections and cant seem to find the problem. Fuses are good. The seat safety switch has not worked in a long time - must have been bypassed at some point - the machine was used when I bought it. I'm not sure how to check the safety switches under the control arms.

    Second problem is once I get it started with the hot wire method it dies as soon as I turn the choke off. I pulled the carb and cleaned it but it still does the same thing. Do I need a carb kit?

    I wouldn't think that these two would be related but I am no mechanic. Most of the time I drop stuff off at my local shop but they are two weeks out.

    Any input and/or suggestions would be greatly appreciated.
    Thanks, Steve
  2. DT Lawn Care

    DT Lawn Care LawnSite Senior Member
    Messages: 850

    Your mower probably has a wiring connection to the bottom of the carb, there should be a nut/bolt for a connection, that could fix your problem/problems. I don't know a lot about them myself, except that one of my Kohlers has this and I've heard of other problems that people have had with this.

    Restrorob should be able to help you out here if you can't figure it out, just go ahead and post the model and serial numbers for him. Good Luck
  3. trailboss

    trailboss LawnSite Member
    Messages: 206

    I found a few numbers but I'm not sure if they are what we need. Scag SSZ-20CV & the only number that I can see on the motor is 5AE PPG F40. I also have the serial number of the mower if that helps.
    Thanks Again!
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    As mentioned it's not likely these problems are related, As DT mentioned is there a small solenoid on the bottom of the carb ?

    The joystick safety switches can be tested with a multimeter set to ohms scale, Un-plug the switch and put the tester leads on the switch post matching the corresponding wire colors.

    Now here's the tricky part to explain; With the switch plunger out one side will read a closed circuit while the other will read a open circuit, Now push the plunger in and you should get reverse readings. The side that was closed before should be open now and the open side should be closed.

    Any other variation from above indicates a faulty safety switch.

    From the model number it appears the engine is a CV20, But the serial number would confirm this.....
  5. trailboss

    trailboss LawnSite Member
    Messages: 206

    The serial number on the mower is #21460163.
    What does the solenoid on the bottom of the carb do?
  6. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Messages: 296

    You say you turn the key and get nothing. No cranking no nothing right? If that's the case then it sounds like a bad diode in the start circuit not letting power to your starter solenoid. If it won't even turn over there is no need to start messing with the fuel solenoid.

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