John Deer hard to start

Discussion in 'Mechanic and Repair' started by c1gmlm, Dec 2, 2002.

  1. c1gmlm

    c1gmlm LawnSite Member
    Posts: 7

    I have a JD LX172 lawn tractor thats hard to start. The plug lasts about 2 mowing sessions. I have been using Champion plugs, RN11YC4. Whie cranking th engine spits and sputters, sometimes backfires. I change theplug and away it goes and runs fine for the rest of the day. Any ideas? Thanks in advance.

    Mike
     
  2. sdwally

    sdwally LawnSite Senior Member
    Posts: 385

    Change the brand of the plug to either NGK or Nippon Denso. In the smaller engine, you'll have less problems with fouling.
     
  3. Remo Sid

    Remo Sid LawnSite Member
    from USA
    Posts: 55

    The brand of s-plug is not the main factor here. you need to find out why the s- plug is not holding up. When you take out the (bad) s-plug, what does it look like, (what color is the tip?) No matter what brand s-plug you use, it will foul if the engine has problems. Let us know about the apperance of the used s-plug and we can go from there.
     
  4. c1gmlm

    c1gmlm LawnSite Member
    Posts: 7

    The plug is usually wet and has some carbon on it. I dry it off and use a wire brush to clean it and regap @.28 It seems that this doesn't improve anything. So far just changing to a new plug works. Thanks for your time.
    Mike
     
  5. Remo Sid

    Remo Sid LawnSite Member
    from USA
    Posts: 55

    Lets get a little more specific. We need to determine the substance on the plug.

    The plug being wet...is this before, or after you have tried to start it?

    The "carbon"...what color is it? Is it hard, or can you wipe it off with your hand?

    If the plug is wet from oil, the plug probably has a carbon buildup.
    You will need to determine how the oil is getting in the cylinder.

    If the plug is wet from gasoline, you will need to determine why the excess fuel is entering the cylinder.

    Answer the questions, and we will go further.
     
  6. c1gmlm

    c1gmlm LawnSite Member
    Posts: 7

    The plug is wet after cranking engine, about 1 min. The black "carbon" can be wiped off with a cloth. If oil is entering the cylinder why wouldn't the engine smoke when it is running? Once it gets running, it runs great. Tonight, I wiped off the plug, check the gap, while cranking the engine(choked) it backfired a couple of times but wouldn't start. I now have it on the battery charger. Could the cold weather (Michigan) have an effect? Thanks for your time
     
  7. Remo Sid

    Remo Sid LawnSite Member
    from USA
    Posts: 55

    OK...the problem is too much fuel getting to the cylinder. What you are seeing on the plug is soot, not carbon. Several things can cause this. Eliminate the easiest first.

    Check that the choke is being fully opened after the engine starts.

    Check that the air breather is clean.

    If both these check out ok, then you have internal carb problems. Could be trash preventing the needle from maintaining the proper level of fuel. Could be a hole in the float. Could be the atmosphereic pressure vent clogged.

    Yes, extreme cold can make gasoline engines harder to start, and stress them more than usual.
     
  8. c1gmlm

    c1gmlm LawnSite Member
    Posts: 7

    THe air filter is clean and the choke seems to working properly as I move the throttle. I didn't know where the vent was to check that. Again I tried to start it and it turned over afew times, almost started, backfired a couple of times. It's backon the charger now.
    How technial i checking out the carb.
     
  9. MikeLT1Z28

    MikeLT1Z28 LawnSite Bronze Member
    Posts: 1,732

    i wouldn't rule out a weak spark issue either, especially with the engine trying to start and backfiring then leaving unspent fuel on the plug. i had a small engine acting this way once and it was a weak coil.
     
  10. c1gmlm

    c1gmlm LawnSite Member
    Posts: 7

    Where is the coil located? And is it easy o check/replace?
    What about carb adjustment? Last time I tried to start it and checked the plug, it was dripping with gas? Thankfully we haven't had any snow !
     

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