Questions about 18 hp B&S vanguard

Discussion in 'Mechanic and Repair' started by Watkinslawnservice, Jun 5, 2005.

  1. Watkinslawnservice

    Watkinslawnservice LawnSite Senior Member
    Messages: 378

    :help: I have a '98 Great Dane Surfer with a 18 hp Briggs Vanguard OHV recoil start V-twin engine. All of a sudden it started running a little crappy, but never kills. It started blowing a good amount of black smoke and it lost a lot of power. I changed the plugs because they were both as black as could be. This didn't seem to help though.

    My next idea is to check compression. My question is: what should the range of compression be for this engine? Is there anything else I am missing here? I have a funny feeling that I lost a cylinder but I won't know until I do the compression check.

    Thanks for any info or help you can give me on this.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    100 to 125lbs comp.,But I'm leaning towards water or trash in the carb.,Loss of one cylinder will not make the engine run as you discribed.
  3. MastercutzLawnCareII

    MastercutzLawnCareII LawnSite Member
    Messages: 27

    Check to make sure your choke cable ain't broke, or slipped a lil allowing the choke to close not completely but just enough to cause it to run a lil rich, Mine done the same thing the other day and when I would back off the throttle some it would smooth out and be ok, by the black smoke I would say its defiently something to do with fuel......
  4. Watkinslawnservice

    Watkinslawnservice LawnSite Senior Member
    Messages: 378

    You guys are both right on the money. Thanks for the help but we can call off the dogs now. It turned out to be just a dirty air filter! I checked the air filter the very 1st thing I did, and it was a little dirty but I didn't think that it was dirty enough to cause problems.

    I did the compression test and I had 130 lbs in one and 140 in the other, so I narrowed it down to a rich fuel problem just as you guys already said. While it was running I took off the air filter to look at the carb and VOILA it smoothed right out and quit blowing black smoke. It was just starving for air!

  5. Redneckn

    Redneckn LawnSite Senior Member
    Messages: 294

    compression checks suck.. run a leakdown on it.
  6. lawnman25

    lawnman25 LawnSite Member
    from Kansas
    Messages: 22

    I haverun them for several years and they are real sensitive about dirty air filters. Even when you blow them out they can still be plugged enough to cause them to smoke and lose power. If you start noticing loss of power always replace the air filter first.

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