Toro Lawnmower Air Filter: Additional Small Diameter Tube; Purpose ?

Is there the slightest chance you read the owner's manual or visited their web site?

The make and model of the engine ? " 22 inch Toro, a few years old " .. isn't much to go on. John T.

I have a Champion generator that has a little tube between the air filter and the gas tank. I don't know the purpose of that either. Perhaps to filter the air entering the tank.

or to burn in the engine the vapors from the tank.

Burning the vapors is probably the reason. Years ago cars had what was called a road draft tube. It was a tube that came from the crank case and pointed down to the road to vent any vapors in the crank case. Later they came out with a PCV valve that usually came off the valve cover and back to the air filter housing. This was an atempt at keeping the air we breath cleaner, not the engine.

Is there the slightest chance that you could post a link to ANY mower manual that describes how that tube works.

.. Now .. Now .. Please children - settle down.

.. Children .. Put that down ! ..

No ! Don't throw that ! ! ..

.. or was it Frank Zappa ..

John T.

never mind all that. Seems Toro really has amped up its product line, based upon this gem I found:

"The spark plug, powered by a ****magnetron**** attached to the engine flywheel, ignites the fuel, which forces the piston down and turns the engine crankshaft and the lawnmower blade attached to it."

Why? I don't give a s*it what it's for because I don't have a small tube. :-)

Crankcase breather? (usually more like 3/8 to 1/2 inch, but?? )

VERY unlikely to be from the gas tank to the air inlet, as a backfire could then light the tank. Generaly there is a tube from the crankcase vent to the air cleaner (My Champion generator, my Yamaha snow blower and my Bolton (CHONDA clone) engine on my lawn mower all have them. The only "fuel" line I have ever seen terminating in the air-cleaner housing is a primer line, which can be run from the tank - but more often the float bowl, through the primer bulb, to a pint just ahead of the carb and behind the air filter.

I didn't see anything interesting there. I won't put words into the OP's mouth. For a Tecumseh carburetor, the tube I'm talking about is a rigid plastic tube that lodges in a hole that vents into the top area over the float valve. It sticks out at an angle and pokes past the intake and about half an inch into the air cleaner.

This is NOT the crankcase breather. That's a larger tube that goes from its own carb port and disappears under the flywheel cover. Nor is it the outlet for the primer pump. Primer pump gas comes out a different hole.

All the Tecumseh mower carbs that I've seen have the hole for the tube. Only some of the engines have the tube installed. Since I get all my lawnmowers as junk, it's possible that the previous several owners lost the tubing.

I wonder if it has something to do with starting. Without the tube, the carb bowl vents into the intake area. It's hard to suck any gas thru the jet if pressure is equal on both sides. Yes, the venturi sucks out the gas, but while starting, the air velocity is relatively low and there ain't much suck. It's possible that the tube venting into the air cleaner where the pressure is slightly higher, might make it easier to get gas sucked into the airflow while starting.

I found some tubing about the right size. I'll test that theory next time I mow the yard.

That's my 2-cents on the subject.

I misread the discription of the tube. Thought it was the one going to the crank case, but now see it is from another place.

OK - you are talking about the bowl vent. It allows filtered air into the top of the float bowl and does return vapour from the carb to the intake.

cars used to have a small tube between the carb above the throttle and the fuel bowel to equalize the pressure drop across the air filter so that the metering didn't get too out of cal by a dirty air filter. m

Ok, but that happens with or without the tube installed. What's the purpose of the tube?

Taxed and Spent posted for all of us...

Damn, a microwave on a tractor, I'd think they would have put a refrigerator for the brew ski. Maybe it for winter use to heat up hot pockets while blowing the snow. IDK.

Like I said - it puts CLEAN air into the float bowl. Take the hose off and it gets dirty air - not much other effect.