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Lawn Boy Duraforce issue....

Discussion in 'Mechanic and Repair' started by boonhogganbeck, Apr 13, 2008.

  1. boonhogganbeck

    boonhogganbeck LawnSite Member
    Messages: 45

    Hi everybody. I've got a Lawnboy Goldpro with the 2 cycle Duraforce 6.5 hp engine. Typically, I push the primer bulb three times, choke and it starts on the first couple pulls. Friday evening I was trying to get my yard cut before a storm moved in. I usually cut the front yard and then immediately move on to the back. However, a realtor was showing my house Saturday morning so I went ahead and shut the mower off and blew of my sidewalk, driveway, and front porch in case the rain started before I finished cutting the back yard. I guess this took 5 - 10 minutes (also went inside and had a glass of water). After that I came out to mow the back yard and couldn't get the mower started at all. Any ideas or tips??
  2. Roger

    Roger LawnSite Fanatic
    Messages: 5,943

    Whew!!! "Been there, ... done that," on far too many occasions with my DuraForce LB.

    Has it been used extensively? By that, does it have many hundreds of hours of use? Since it is a GoldPro, you may be a homeowner, not a contractor. If the case, then perhaps you have very few service hours on the machine.

    I run a LB Commercial mower, with a DuraForce, and have had big headaches for a long time. But, it has seen hard and long use. After a couple of years, it has a second carburetor, and two new short-block rebuilds. But, part of the troubles along the way echoed your description. If I was to suggest a first place to look, the carburetor. Is the post that passes through the throat of the carb worn? The bottom of that post (this is the one with the air vane on top, used to control the governing action of the carb) fits into a blind hole. When my starting troubles were the worst, I found the post fitting into that blind hole was ovalized from wear. Later, I learned the blind hole itself was badly oversized from wear too. That is what prompted a replacement carb.

    Having said that, one thing that I can say with confidence, "The only constant with the DuraForce is change." I mean that it will work fine for three days, and not work well the fourth, for no apparent reason. Then the problems disappear, only to show up again later. If it runs well for a few days in a row, I can count on some bad days in the near future.

    Even this Spring, it now runs terrible. Last Fall, it ran very well. This Spring, it surges, does not hold a constant governed speed -- unless it is under heavy load. Why this behavior? I surely don't know, but am content to live with it for a few more days. I would throw it into the nearest river, if I could find a good replacement -- 85-90# weight, mower that bags well, leaves a good mowing result.
  3. boonhogganbeck

    boonhogganbeck LawnSite Member
    Messages: 45

    I'm a homeowner. It's been used every week or two during the warm months for the last three years. Cuts and mulches very well. It is on its second carb. I count that as my fault for leaving fuel in it over the winter, not emptying the tank and burning out what was left. My dad bought a Honda in 1990 that now belongs to my brother. It still starts on the second pull every time. Maybe I should have learned something from that :confused:
  4. Roger

    Roger LawnSite Fanatic
    Messages: 5,943

    With only three years, a hour/two per week for 30 weeks or so, that means it may have about 100 service hours. That is very low hours for that engine. You don't say when the carb replacement was done, but it must have 60 hours, or less. That should not be the problem.

    I suggest taking out the spark plug, ... no, check that, replace the spark plug. It may be the original plug. Also, be sure the air cleaner is clean. Take out the foam cleaner, and wash thoroughly with soap and water, let dry, put some engine oil (sparingly) on the cleaner, and return. There is no need to replace, just be sure it is clean.

    Since you asked the question, I presume that it has always started well in the previous years' service, right?

    Mine has gone through periods of this behavior -- finishing one property, loading on the trailer, driving for a few minutes, unloading, and then, ... hard to start. Cold start was fine, but warm start, not fine. Hot start was fine too, but it was the warm start. That is not my problem now, but has been in the past. My best explanation relates back to the worn out carb.
  5. boonhogganbeck

    boonhogganbeck LawnSite Member
    Messages: 45

    The carb was replaced after year one. I replaced the spark plug and cleaned the air filter as you described. Same thing here - cold start is fine, hot start is fine (like after just emptying the bag when I use it), but the warm start is the problem. I do usually have to pull on it some the first time out in the spring, but after that it cold starts pretty easily throughout the summer. I did some testing this afternoon. I started it and let it run for about twenty minutes (I clamped the handle down), turned it off, waited about thirty seconds and started it right up again. I waited five minutes and it started right up again. I then waited fifteen minutes and it wouldn't start.
  6. Jay Ray

    Jay Ray LawnSite Fanatic
    Messages: 6,510

    On mine sometimes 5 or 6 slow pushes on the primer bulb will work when it balks. It seems like it would flood for sure, but it has worked for me. I'm not saying this makes any sense, just that it has worked.
  7. boonhogganbeck

    boonhogganbeck LawnSite Member
    Messages: 45

    Thanks, I'll try that.

    Has anyone on here tried rejetting the carb as is discussed on some other forums? It seems like LB made the carb run really lean in order to appease the EPA. I've read were this stops the surging.
  8. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Messages: 3,711

    2 issues with duraforce-you must install a fuel shut-off and use it after EVERY USE.OTHER WISE the needle valve will leak down causing a flooded restart condition-second -the ignition module is prone to failure -works fine when cold-but after heats up-no spark. only cure -replace module. best not to depend on a duraforce as your sole 21 mower-sad to say-when working -they kick but
  9. Jason Pallas

    Jason Pallas LawnSite Bronze Member
    Messages: 1,335

    BEFORE you do anything else DO THIS. The next time it won't start pull the spark plug and test to see if you're getting a good spark. My guess is that you have a faulty ignition coil/module - causing the erratic starting.
  10. sawman65

    sawman65 LawnSite Senior Member
    Messages: 754

    coils coils coils i have a bucket full of them

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