Yanmar engine wiring

Discussion in 'Mechanic and Repair' started by Diesel Nut, Sep 21, 2007.

  1. Diesel Nut

    Diesel Nut LawnSite Member
    from Alabama
    Posts: 2

    I am going to do an engine swap on my old John Deere lawn mower. I need a little bit of help figuring out how to wire up the new engine. The engine I am going to be swapping in is a Yanmar 2V78C-TX. The guy I bought the engine from had it wired up to test run it. After I got home, I changed the oil and had it running for about a minute when something exploded on the engine. It was smoking very heavily, but it was still running. I shut it down as quickly as I could and disconnected the battery. The engine stop solenoid overheated and exploded. I think something was not wired properly causing it to overheat. There are three wires coming out of the solenoid; a red, white, and black wire. Also, I was looking at the wiring on the voltage regulator. There are three wires that were cut that I need to know what to do with them. One of them is a heavy gauge red wire which I assume goes to the battery and the other two I haven’t a clue. I have looked all over the internet for a wiring schematic with no luck. Does anyone know where these wires go? I have a new solenoid coming and I don't want to blow it up too. Any help is greatly appreciated.

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  2. Leaf Jockey

    Leaf Jockey LawnSite Senior Member
    Posts: 360

    OK, I'll try this again. I hope its not a duplicate post. Of the three wires on the fuel solenoid, one is a ground. One is an energize circuit. This is powered only for a short time, usually while cranking. This is the circuit that pulls the lever in. The last wire is the hold circuit. It holds the lever in and draws less power. If you wired the energize circuit to the battery then I suppose it overheated.

    Scott
     
  3. fixer67

    fixer67 LawnSite Silver Member
    Posts: 2,104

    BLACK WIRE=GROUND
    RED WIRE=HOLD
    WHITE WIRE=PULL IN

    The black wire goes to the frame. The red wire goes to a key switched (+) and gets power at all times the engine is running. The amp draw on the RED wire is only about 3 amps. The white wire is the pull in lead. It ONLY gets power as the starter is turning. When the starter cuts out so does the power to the white wire.
    The amp draw on the white wire is over 30 amps. If the white wire is powered for more than 30 seconds it will over heat the fuel solenoid and it will destroy it. The cost of a new fuel solenoid if about $150.
    I just replace one on a generator about a month ago.
     
  4. Leaf Jockey

    Leaf Jockey LawnSite Senior Member
    Posts: 360

    Thanks. I figured it best not to guess on the wire colors.

    Scott
     
  5. Diesel Nut

    Diesel Nut LawnSite Member
    from Alabama
    Posts: 2

    Thank you very much for the help with the solenoid. Do you have any idea where the wires go on the voltage regulator?

    Thanks
     

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