Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

While typing this request for advice, I decided to try one more thing and found the problem!

PROBLEM: When starting, it sounds great for about 2-3 seconds and then slows way down and coughs out black smoke.  Occasionally there is a metallic ping.  The power output is too anemic to mow anything but the lightest grass growth.

The mower is nearly new (bought last year) and had operated perfectly until my son last week tilted it backwards a lot to handle 11 days of grass growth.

The paper manual and the online guides at briggsandstratton.com say it's OK to tilt the mower backwards, but not forward.  However, I suspect the tank was full at the time (due to a telltale "bathtub ring" left by gasoline on the body of the mower just below and surrounding the base of the engine) and so I think a lot of gas poured out while he was mowing and somehow got into the air filter, even though the filter is forward of the tank top.

SOLUTION:  Took out the air filter (one screw holds a hinged cover over the filter) and started it and it runs fine!

The air filter reeked of gas even after one week (I had naively assumed any gas would have evaporated by now).  As it's running, if I slap the filter back in place, it slows down again after a 2 second delay.  (That's how long it takes to run out of oxygen, I guess).

Finished lawn with no filter, crossing my fingers all the while - even though that makes it harder to hold the safety bar.  :-)  :-).

ACTION:
 1) Try to dry the filter out by suspending it in front of a floor fan all night.
 2) If this doesn't work I'll buy a new one - hopefully no more than $5.

HOPE THIS HELPS SOMEONE ELSE!
Larry, mowing my Mile Hi lawn in Fort Collins, CO.

Larry
Paper filters have a way of "closing up" it seems like after being soaked in anything, including gas. so for the price of a filter, its best to just replace it. also check the oil and see if it smells gassy and perhaps over full. fuel thinned oil isnt as effecient at lubricating, & will tend to seep past the rings when running, causing some smoke as well. change if necessary.  its always possible you have fuel in the crankcase as well.
At least lawn mowing is slowing down in the collins area now (i know the area well, Greeley native myself) we have another 2 months of "summer mowing yet here.
Try those suggestions and see how it runs, that should take care of the problem.

Thanks for the advice, SpottedPony!  I'll check out the oil.

BTW - drying out the gassy filter in front of the fan all night did help a lot, but nowhere near enough.  So I bought a new one.

-Larry