Basic Engine Question - 8HP Briggs won't start

Discussion in 'Mechanic and Repair' started by buzzard86, Jul 21, 2007.

  1. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Posts: 923

    The carb "assembly" is everything contain in box 125 in the manual.
    The nozzle should be a press fit, but don't try to remove it just yet.
    Take the spray tube from your can of carb cleaner and try to force cleaner through the nozzle. You see/hear is "woosh" into the carb air intake body if it's clear.
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Jim,

    Remove the air filter cover, Behind the air filter you will see two nuts and down below them a screw. Remove all of these and carefully remove the air filter base, Make sure to carefully remove the breather hose (it could be rotten from sitting).

    Once the base is off you will see a torx (star) on the end of the two studs, This is where a torx socket is installed to remove the carb mount studs.

    If you don't have this torx socket use two regular 1/4" nuts (without the flange) and screw them both on one stud, Jam (tighten) the two nuts together then put your wrench on the nut closest to the carb and remove the stud.

    Do this on both studs and the carb will come off, This engine also has a fuel pump mounted on the flywheel cover. Once you get the carb cleaned and re-installed before putting the air filter and cover back in place spray some carb cleaner in the carb and try starting, You may have to do this a couple times to get it to stay running.

    It takes eight or so pulls for this impulse fuel pump to fill a empty carb for it to stay running, The carb cleaner prime saves a few of those pulls.
     
  3. buzzard86

    buzzard86 LawnSite Member
    from Philly
    Posts: 52

    Thanks, guys. I'm going to head back out and tinker with it today. I'll let you know how it goes.

    Rob, I was going to PM you directly but was afraid that you wouldn't want to get involved with another one of my small engine projects. :laugh: Still have to enlist your help to make some adjustments to the Scag drive belts but it's running beautifully so, as you can see, I've moved on to other projects.

    Thanks again, everyone.
    JIM
     
  4. buzzard86

    buzzard86 LawnSite Member
    from Philly
    Posts: 52

    Update:

    I again saturated the carb with carb cleaner and did a few cycles of carb cleaner followed by compressed air. Couldn't tell if I was getting the "whoosh" and it still wouldn't start, so I wound up pulling the entire carb. With the carb off, I can see a mist of carb cleaner if I shoot the air up the jet. However, now that I've got it all pulled apart, I think I'd like to soak it to give it the best cleaning possible.

    Can I just submerge the entire carb in solution? And what's the recommended stuff to use?

    JIM
     
  5. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    Are you sure you have the carb ALL the way apart ? Make sure you take the main nozzel out. Spray carb and/or choke cleaner in all open ports. Then use 120 pounds of compressed air.

    If you want to soak the carb go to NAPA and buy a 1 gallon can of carb soak. Be careful because it will swell up anything but metal or nylon. Once you soak it for about 1 hour then spray it out with 3M brake cleaner then follow with compresed air. Then it would be a good idea to install a rebuild kit. Good luck!
     
  6. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    I wouldn't recommend soaking this carb, There is a rubber throttle shaft seal that WILL swell up and either protrude from between the carb body and shaft or cause the shaft to be stiff and hang up.
    Then the throttle shaft must be removed to install a new seal, In some cases the throttle shaft butterfly screws break off in the shaft so a new shaft is required.

    Look at the tip of part reference #147 pilot jet and make sure it's open, A bristle from a hand wire brush is good for opening this small port before spraying choke cleaner through the tip of it.

    On some LMT carbs the main jet is incorporated into the bowl nut Ref. #950 so check that and make sure those ports are open also.

    A good proper cleaning with carb & choke cleaner followed by compressed air as others suggested should be plenty clean enough to get this thing up and running.

    Good Luck
     
  7. buzzard86

    buzzard86 LawnSite Member
    from Philly
    Posts: 52

    OK, I carefully read everyone's recommendations (thank you, thank you) and did not soak the carb. I carefully cleaned the carb with just the spray and compressed air and put everything together. Wouldn't you know, it started right up!!!

    Ran beautifully for about 2 minutes and then started to cough and sputter. Still runs but not smoothly. I'm presuming that I probably sucked some more junk into the carb. Now that I know how it comes apart, I guess I'll just take it apart and clean it again.

    Incidentally, after it started I discovered that the on/off switch is broken and stuck in the on position. Anybody know where I can source a new one?

    Thanks again for all of your help, gang.
    JIM
     
  8. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Posts: 923

    Flush the fuel line from the tank.
     
  9. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Check/clean the fuel tank this time and replace the fuel filter.

    Look the switch part number up in the IPL you have then enter it in the part search box then click add to cart and purchase it.

    http://www.briggspowershop.com/BriggsAndStratton/advancedsearch.aspx

    Or you can hit your local dealer.

    Also, If the center part of the kill switch is loose/comes out, The kill wire could be dangling around inside the flywheel cover shorting out causing a radical run situation.
    I just repaired one last weekend doing this same thing.
     
  10. buzzard86

    buzzard86 LawnSite Member
    from Philly
    Posts: 52

    Thanks, Bill and Rob.

    Rob, I'm curious... what do you mean by a "radical run situation?" I thought for a brief moment that I may have seen a spark come out of the switch hole (the broken switch handle rattles out so there's just a hole), but didn't see it again and just thought it was an illusion. Wondering now if it may be shorting out.

    I did change the fuel filter and drained the tank completely before I began any of this. Also changed the oil.

    Do I pull the whole motor housing off to replace that switch? I looks to be mounted directly in the housing.

    JIM
     

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