Small Engines (Lawn Mowers, etc.): Engine bogs down and cuts off!, blue flames, hi tension

Question
I have an older snowblower that starts fine blades turn but when I start to blow the snow the engine bogs down and blue flames shoot out of exhaust usually shutting down the blower! I have took bowl off and sprayed carb cleaner into holes but it just doesn't seem to work! This has just started in past week! We had a big snow right before christmas and it worked fine! I love this snowblower and really need it to work right now! Please help

Answer
hi derek    from what you tell me   compresion may be ok for no load  running but may not be for loaded running

with flames out the exhaust may be worth while checking out timming , ( flywheel key  bent ) could also be spark gronding somewhere intermittantly too -  and possibly tight ex valve clearances  or burnt exhaust valve face / seats   as too the bogging down  sounds  like  a fuel flow problem as well   - have a look @ fuel flow from tank to carb and strip and check carb for blockage in the progession ports and air bleeds  , check main jet could be restricted,   check spark breaking down under load  - ?  have shop test it for you

you could make a tester  

find 20 mm thick piece of wood and 50 mm  square
drill  20 mm hole in middle - mark middle & centre of 2  opposite ends  and drill hole  to fit an sharpened nail  - fit 1 nail in each side and push in until you get a gap between the sharp nail ends of no less than 6.00 mm     conect this between the hi tension lead  and the spark plug  and  run engine if spark is not jumping this gap and has a problem you will see it happening in the tester     this helps identify visually  spark problems


hope this gives some ideas   cheers paul