Husky rider w/20hp Kohler Magnum (1995ish). Spec #57528.
For a long time it ran rough. Surges a lot. Throttles up slowly. Blows
black smoke when throttling up. I'm told this is carb problem.
The other day I'm mowing and its running rough and surging. When the
rpm's are on the way up it blows black smoke. But after a while it
starts to stall out. I shut off mowers and it gradually gains rpm's.
Mowers on...dies. Mowers off...slow recovery. I drove back to the
house and it died. Wouldn't restart.
Checked spark. None sometimes or very weak. Found that the spark plug
wire connector is rusted and starting to crumble. Ah hah! Could the
slow deterioration of the connection cause a bad spark which caused
the rough running and black smoking? Soooo, I replaced spark plug
ends. It started up. Ran rough. Sooo, I took the carb off and tore it
apart and soaked it in cleaner. Reassembled. Started immediatelly.
Still gains rpm's slowly. Turned mowers on. Engine immediately dies
just like if the key is turned off. Turn the mowers off and engine
gains back it rpm's.
Any ideas? I'm stumped.
How old is this mower -- does it have ignition points or modern transistor
ignition. It sounds exactly like my 30 year old Troy-bilt tiller. If I
didn't engage the tiller tines carefully it would stall or would only slowly
build up revs. The points were dirty and needed replacing. Followed my
manual exactly in regard to installing the points and how to re-time the
engine while replacing the points which required removing the head. While it
was open, I scraped carbon off the piston and the inside of the head. Put it
all back together and fired it up. The old engine fired up immediately and
had its old power back like a new engine. This was a 30 year old Tecumseh.
Black smoke is a fuel issue, running too rich,
While smoke, in an air cooled engine as you have, would be oil.
Either issue can, and will foul the plug.
Putting a new one in, will prob get it to start, but will NOT fix the
underlying issue of a carb problem.
I adjusted carb as well as I could. Still slow on building RPM's.
However, it starts immediately and runs better then before. I did have
to adjust the float. I think it was filling with too much gas. This
might has caused the rich mixture. I think I lowered the float level
about 1/32 or 2/32 inch.
As for the mower problem...I took the drive belt off and started it
up. As soon as I turn the mower switch (electric clutch) on the engine
putters down till it shuts off. Seems to be identical to turning off
the ignition switch, and also identical to what it does with the mower
drive belt attached.
I'm thinking electrical short. What caused it I can't imagine. But how
do I tell if I'm losing ignition when the mower is engaged? Or, what
else should I look at for a clue.
This is an addition to a reply that I posted a few minutes ago.
I just started the engine with a spark tester attached from the plug
wire to the plug. When running the spark looks very weak and when I
trun on the mower switch the spark disappears and the engine dies.
Hmmmmm. What does this point to?
Check the safety interlocks. On some mowers if you try and engage the
deck without the seat interlock engaged it will kill the engine. I
really suspect that you have an electrical problem in addition to any
The engine ignition system should be completely separate from any generator
system they'd use to power the electric clutch. Most small engines use a
magneto ignition system that relies on magnets in the flywheel to move past
a coil to generate the spark voltage. Sometimes they will add a large coil
of wire around the flywheel and let the same magnets generate auxiliary
power to charge a battery or run headlights and the like.
If you have a voltmeter available, can you put it across the battery and
check the voltage with the engine running at a high idle, so it's charging
the battery. You should get 13-15 volts DC there. Then engage the clutch and
see what happens. If all is well, the voltage should remain there. If not,
then it's time to do more snooping.
My best guess about the engine dying when you engage the blade is a bad
safety circuit. The last three riding mowers I have had required the
operator to be in the seat when engaging the blades. You may have a bad
switch, wire or connection. The switch is probably under the seat or is
actuated by a lever or linkage connected to the seat. . As for the slow
acceleration, that sounds like a carburetor or governor malfunction.
It was the switch under the seat. Yesterday when I was riding it and
turned the mowers on it died, just as it did the other day. A friend
mentioned the seat switch and I mentioned that I was on it when it
died. But I went out and tried it again anyway. Guess what. It works
fine. I assume that the switch is going bad and intermittently doesn't
make contact. Maybe its rusty like the plug wire connections were.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.