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Brigs & straton mower help anyone

Post in 'DIY and General non-hearth advice' started by moondoggy, Apr 28, 2008.

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  1. moondoggy

    moondoggy New Member

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    hey,
    bought my mom a sears/briggs mower about 1-2 yrs ago.
    most poorly designed POS mower. (who puts the spark plug up front?? now it shorts out everytime she mows under a bush.)

    It runs, but is always reving up and down, up and down. constantly.
    I am going to change the oil out, because its black, and so was the plug which i cleaned,
    but there is NO carb adjsutment on mowers anymore? no a single screw??
    the muffler is also black, would that effect it running smooth?
    besides a good clean out, anythign else I should look for / do?

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  2. TMonter

    TMonter Minister of Fire

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    Did she change the oil?

    Most of the newer mowers just need the carb. disassembled and cleaned out every couple years especially if she didn't put stabilizer in at the end of the season. My 4 year old MTD mower is notorious about this. Also check for water in the gas tank and a dirty air filter, black muffler indicates a rich condition which could be air filter.
  3. moondoggy

    moondoggy New Member

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    no, and oil can not get any darker. thats what i'm doing next.
    The filter i bang out constantly for her. always dirty
    Does STABLE go bad? i think the can she used was real real old but that stuff never goes bad i thought.

    yes, that spring is all the carb relies on... oddly. you can see it flexing as the mower revs up and down, not hung up.... but now that i think of it, it is not
    the perfect condition spiral that it was when new... perhaps i should look to replace that too, thank you

    probably jsut needs a carb removal and total cleaning, just that its less then 2 yrs old, and i didnt want to do a total teardown....i'm bound to
    bust something in removal .....its just me
  4. moondoggy

    moondoggy New Member

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    yea tried some of that... need another can.
  5. Highbeam

    Highbeam Minister of Fire

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    Two year old briggs running that poorly almost certainly is due to bad fuel. My bet is on the carb all gummed up with junk.
  6. Redox

    Redox Minister of Fire

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    Is Briggs still using the old diaphragm/gasket on their vertical shaft engines? They used to deteriorate every other year or so. My mower guy used to order them by the case...

    Chris
  7. moondoggy

    moondoggy New Member

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    nope, no carb adjust that i can find......
    and the fuel should have been fine, my mom has some dry/dust areas and the mower seems to be always dirty.. its probably dirty/clogged somewhere.
    guess i am gonna pull it apart.
    not sure about the gasket... gotta look at the book again.
  8. JustWood

    JustWood Minister of Fire

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    Clean the carb and remove tank and clean and check your gas can for residue. Wouldn't hurt to keep your gas can out of the sun, this can cause condensation. Add isopropyl to gas can every fillup to take care of any moisture.
  9. brad068

    brad068 Feeling the Heat

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    Pinch the fuel line or drain the gas out. Take the bottom plug out of the bowl on the carb. Watch so you don't tear or stretch the square o-ring around the perimeter of the bowl. When the plug is removed the bowl may or may not fall with it. The main plug -think its 1/2"- has a sleeve on it that has a main jet in it and a little hole on the side that lets gas into the main jet. My bet is that hole or the main has some green varnish in it not to mention the whole bottom of the bowl. Carb cleaner doesn't work on this kind of varnish. The only way to really clean a varnished up carb is to take it off, disassemble it and soak it in Simple Green that stuff is the best thing that I've found for cleaning carbs. These new motors have no carb adjustment other that idle speed.
  10. mjbrown

    mjbrown Feeling the Heat

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    thank you for this bit of info.i have a push mower that was on its way to the scrap yard because it wont run and it looks like new...now i will tear it apart and check this out. fyi, sea foam does an awesome job on carbs as well

    mike
  11. Czech

    Czech Minister of Fire

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    Paint thinner too!
  12. EatenByLimestone

    EatenByLimestone Minister of Fire

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    I've found that that little spring can stretch too. A pair of needle nose will shorten it if you find that is a problem.

    Matt
  13. burntime

    burntime New Member

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    C'mon hunting season!
    Get a product called sea foam at your farm and fleet or tractor stores...maybe even a boat store. Dump ALL the gas and get fresh with the sea foam. Start it and go about your mowing...by the next time you mow it will have cleaned the carb out. There is no adjustment on them, they are throw aways...sad to say a good pushmower nowadays is a toro or honda and they are 450.00 plus.
  14. moondoggy

    moondoggy New Member

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    you guys are great.
    here's where I'm at:
    did the oil change-BLACK- cleaned as best i could w/out removing carb... thats a longer project then i had time for... or honestly trust myself with.
    there is no adjsutment as burntime said-- thesemowers are like throw away items.

    - i start it up, perfect on first pull as always- runs great for 2 minutes then gets to reving up and down... high and low a lot.
    i remove the plug- black again. there is soooo much carbon built up inside that hole its amazing.
    i think that is my problem- just so much dirt/carbon on the head.
    this mower is only a year old :(

    can i use this seafoam or an auto injector cleaner for that?
    I really run it just on seafoam- no gas?
  15. burntime

    burntime New Member

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    Seafoam will clean the entire engine. You need to mix it with gas. If you really want to go crazy dump some seafoam down the carb until it chokes out. Let it sit overnight, add gas and seafoam and start mowing. My neighbor had a snowblower that was sitting for 3 years with old gas. I drained it all, drained the carb (you would have to run it dry) and added gas and seafoam. Ran it for 10 minutes in the drive and shut it off, did this 3 times on a saturday. Sunday came and started it up and it ran great. Check the can, I think seafoam is also form of stabil!!!
  16. burntime

    burntime New Member

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    C'mon hunting season!
    If its really bad you may need to pull the head to remove the carbon. Sounds like it is running really rich? I forgot, did you say you checked the air cleaner? If it is full of crud it will limit air and you will get a really rich mixture.
  17. moondoggy

    moondoggy New Member

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    ah, ya know, i mentioned that it (the air filter) is always clogged.. constantly cleaning clumps of dirt.
    it is clean now, but that would cause it to run rich as you said and black buld up.
    and man, if i pull the head, i'm gonig to break something that wasnt broken. its jsut me.
    picking up the seafoam at pepboys at lunch. hope that helps.
  18. burntime

    burntime New Member

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    C'mon hunting season!
    Absolutely it would run rich with a dirty air cleaner. It custs the air supply just like choking it. Seafoam is 5 bucks and you are only gonna use like a quarter or eighth of a can...cheap fix if it does the trick!
  19. moondoggy

    moondoggy New Member

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    ha, i just picked it up at ~7.00
    ah oils @ 121. a barrel so much for 5. bucks.
    whatever.

    but it will probably be worth it.
    gonna try tonight.
  20. Mmaul

    Mmaul Minister of Fire

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    Does that mower have a self adjusting carbertor? your do you have to choke it?
  21. moondoggy

    moondoggy New Member

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    there is the dopey prime button, push lever forward, pull cord mow.
    and the carb runs off the spring lever.
    i cant find anything anywhere to adjust.
    i chk the manual 3 times. nothing

    think burntime is right, they are set, there are no real adjustments.... like a thowaway mower.
    as i said its kind of sad for a Craftsman/Briggs mower.
    quality isnt too bad, but designed poor.. like by people who have never had to mow a lawn.
    -the sparkplug is up front, so when you mow up/under a bush it touches and shorts unless you back up fast.
    -that carb spring is above left of the plug, gets snagged on things, and crudded up.

    YA KNOW now that I think about it, the air filter is up front too, above the spring, the dirtiest part of the mower. if rotated to the back of the mower, it would really eat less dirt.
    IF they rotated this engine around (the way i remeber all my mowers as a kid) it would be a much better mower.

    and damn while I'm at it..... I hate these "auto shut off when you let go" levers on all the mowers. i velcro it down when i mow, but then i lose the damn velcro.

    thanks guys
  22. Mmaul

    Mmaul Minister of Fire

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    I have a Tecumseh with the same type of carbertor on it I always empty the fuel for winter shut down but there isnt an adjustment. I think you are on the right track with sea foam.
  23. Beanscoot

    Beanscoot Member

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    I too have an aversion to non adjustable plasticky stuff, but have had good luck with this modern Briggs carb. I had an old mower that I could never get to run right and then I put on a used one of these non adjustable plastic carbs, and the engine has run great ever since.

    I think you could have either a loose air inlet elbow or a bit of dirt still in the carb idle emulsion passage. What this does is starve the engine for fuel, triggering the choke to come on and enrich the mixture. This speeds up the engine, then the choke automatically comes off, and the engine powers out again and drops speed till it triggers the automatic choke and the cycle repeats. Thus the large amount of soot produced.

    Try taking the carb off and cleaning it in gas, then try to peer through the tiny passages with a light source behind to see if they're clear. There should be one big one (maybe .03 or so) and one small one (perhaps .01). Use a strand of wire from small multistrand copper wire to poke the holes clear. For super tiny holes I have used an old accupuncture needle, they're amazingly small. Yes-accupuncture can cure lawnmowers!

    If you have access to an ultrasonic cleaner then put the carb in a detergent solution in it, after preliminary cleaning in a little solvent or gasoline. These machines do an excellent job.
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