08/01/09, 02:10 PM
Join Date: May 2002
How to diagnose Lawn Boy mower problem?
I have an older Lawn Boy Silver Series mower with the 6.5 horse, 2 - cylcle engine.
While some dislike the LB Silver models, this mower has run like a champ since I bought it new in '97. Up until this year, it has run just like the day I brought it home in the box.
It still purrs away when it is running, and almost always starts on the very first pull.
The problem that I am having is that it dies on occasion. It will be running perfectly, and then dies like it is out of gas, but without the starving of on-off-on-off when it finds just another drop of fuel. It'll run perfect one second, and the next second, it is dead as a door nail.
I normally run Amoco or Shell gas, that is advertised without ethanol, but have run cheap pump gas in years past, when I didn't know any better. I have ALWAYS used LB brand oil in the cans, and mix as if I were running a controlled experiment, not just mixing with the attitude of "good 'nuff".
A couple of symptoms that may or may not be a factor:
This mower, since new, has leaked fuel out of the top mounted exhaust, and onto the top of the deck when in the shed. If you leave fuel in the tank, there is a good chance that the tank will be empty a week later due to this leak. I have inspected the mower again and again, but cannot find any leak in the fuel lines...it has to be coming from the muffler.
Sometimes, but not always, on cold starting, the engine will race to high RPM's before settling back down to normal RPM's.
Sometimes, and I am not 100% sure on this...it acts like it is flooded when I try to restart it. It seems like throwing on the choke that it is easier to restart.
It also seems, and I could be imagining this, that the mower is prone to dying when it is pulled backwards. Not every time, but it seems like it dies a little more often pulling it backwards than it does just pushing it forward.
I appears that I have plenty of blue spark at the plug, which I have checked several times.
It also appears ever so slightly that I have a bit more smoke on start up after it dies than it should.
I suspect that the fuel is leaking into the cylinder. I just don't know where or how.
Any ideas? On-line forums that you might know of? Manuals or books that you can suggest?
I just need to figure out where to start with this mower.
Thanks in advance!!!!!!!!
Last edited by clovis; 08/01/09 at 02:12 PM.