Briggs poor acceleration, otherwise runs good

Discussion in 'Mechanic and Repair' started by shopteacher, May 18, 2006.

  1. shopteacher

    shopteacher LawnSite Member
    Posts: 60

    Hey Guys,
    I have a briggs 18 opposed twin, and it runs fine, but when you accelerate, you have to do so verrrrry slowly otherwise she dies.

    I have rebuilt the carb 2 times, got a different carb and tried that, no help.
    I have replace the head gaskets, that helped, but still not right. I have replaced the intake gaskets and new hoses, fresh gas, etc. New plugs also.

    Could it be a coil problem? One of the plugs is black, the other is brown.
    The flywheel is a tad rusty, a problem???

    Appreciate your help!!!!!!!!!!!!!
    Shopteacher
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Are you getting spark on both cylinders ? Is this the same engine you were going to perform a compression or leak-down test on ? If not I would suggest one. Hesitation sounds like the low speed carb. adjustment is too lean which I can only guess your's has one since you didn't post any model numbers. Rust on the flywheel isn't real good but shouldn't effect the electronic ignition.
     
  3. shopteacher

    shopteacher LawnSite Member
    Posts: 60

    Regarding the leak down test, I don't have the tool for that any more. It grew legs and walked out of my class, amazing.

    I had a briggs mechanic come to my house today (for free, how cool) and he pointed out a couple areas in the carb that needed to be cleaned better. He also said the rust wouldn't cause my problem.
     
  4. oldrustycars

    oldrustycars LawnSite Senior Member
    Posts: 301

    my 2 cents...if you're going to work on small engines, get a new leakdown tester. i think they are around 50 bucks at jegs. i always do a leakdown test before going any farther on a small engine. no sense fiddling with the carb on an engine that isnt going to run because its worn out. and please post the numbers from the engine...Restrorob has all the dealer info on this stuff, and will recognize if there was a chronic problem with your engine IF you post the numbers.
     
  5. shopteacher

    shopteacher LawnSite Member
    Posts: 60

    Thanks,
    but one quick question:
    I just found a perfectly good engine at the salvage yard. It runs for a few seconds(thats another thread) but it didn't have any shrouds on it. How do you find the info on it. It's a briggs 15.5 ohv, and it came off of a Scotts riding mower.

    Thanks again
     
  6. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Did you by chance get the model and serial numbers off the Scott's mower ?
     
  7. shopteacher

    shopteacher LawnSite Member
    Posts: 60

    No, but I will go back there again for sure. I will look for any numbers I can find. Finding a running motor in a junk yard was quite a high. Can you relate?
     
  8. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Yep sure can, I'm also a welder fabricator and have a small shop behind my home. I have been picking up scrap metal from my junk yard, I hit the jackpot last weekend picking up 4 angle iron bed frames. I have built many many things from these old frames.
     
  9. shopteacher

    shopteacher LawnSite Member
    Posts: 60

    I found the problem to my poor acceleration problem in the Briggs 18 horse. It ended up being the coil.
    I pulled one spark plug wire off, and it still ran good (like the manual says it should). Then I pulled the OTHER wire off and it died. I had a hunch this was the problem all along because one plug was black and the other brown.

    Anyway, for future reads, coil problems are rare, but this time it caused me to rebuild the frickin carb 3 times, but I am now the wiser.

    This is another mower someone was throwing away. WHAT A HIGH!!!!!

    Thanks again
     
  10. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023


    Hmmmmm , Remember my first post ?

    Glad you found the problem.
     

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