Re: rec tech mower

On 4/12/2025 1:05 AM, John B. wrote:

On Fri, 11 Apr 2025 21:58:01 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 

On Fri, 11 Apr 2025 22:59:48 -0400, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:
>

Oh, and it occurs to me that Jeff should be the one answering your
question! He's probably done this sort of thing more than any of us.

>
I don't have the time.  Short version:
>
Troy-Bilt is a good brand of mower.  I guess "self propelled" means
you have a riding mower.  A model number would be helpful so I can
determine what type of engine you might be using.
>
2 stroke engines (chain saw, blower, trimmer) are very different from
4 stroke engines (generator, lawn mower, go cart, zero turn, lawn
tractor).
>
The basic difference is that you add oil to the gasoline on a 2 stroke
but not on a 4 stroke.  Unfortunately, there are 4 stroke chainsaws
and blower the require the addition of oil in the gas.  If you engine
has an oil sump, oil filler and drain plug, it's a 4 stroke.
>
Another difference is that 4 stroke carburetors have a fuel bowl while
2 strokes do not have a fuel bowl.  If you're going to empty the fuel
system on a 4 stroke engine, don't forget to also empty the
carburetor.  Honda clone engines have a 2nd drain plug on the fuel
bowl for draining the fuel and any water that has accumulated.
>
Bad fuel is a common problem with anything that's been sitting for
more than about 3 months.  Humidity condenses water in the fuel bowl
and gasoline tank.  It takes very little water in either to prevent an
engine from starting.  Remove the fuel bowl and pour the gas into a
white coffee cup.  Allow about 15 mins for the water to settle to the
bottom of the tank.  You can see the dividing line between the water
and gas.  Water in the gasoline looks hazy until the water settles.
>
Old gas also smells very different than fresh gas.  If you don't like
smelling gas, just pour a few a small amount of gas on a brick or
metal plate and set fire to it.  Good gas will burn but old gas will
act like you're trying to burn water, which is why the old gas won't
burn.
>
You might have a "gel" problem, where old gasoline and fuel stabilizer
form a gelatinous goo that plugs up the carburetor.  I suggest you
avoid fuel stabilizer or cycle your mower gas through your automobile
every 6 months or so.  Carb cleaner will soften the gel, but is
difficult to remove from the passages, jets and emulsion tube from the
inside of the carburetor without using an ultrasonic cleaner.
>
Speaking of ultrasonic cleaner, mine is an MH-020A 3.2 Liter.
<https://www.ebay.com/itm/365401504638>
Avoid using a solvent type degreaser.  I use a minimal amount of
dishwashing soap (Dawn Platinum).  The water should be fairly hot (I
forgot the temp).  The work is done by cavitation bubbles, not
solvents.  If your aluminum carburetor turns dark grey or black, you
have either the wrong degreaser or too much degreaser.  Dark aluminum
won't hurt the engine but it does look awful.
>
I'm not going to recommend all the possible ways to test an engine to
see if it runs.  There are numerous videos available on how to start a
4 stroke that won't start.  Basically:
1.  Make sure the mower has oil in the sump.  All the Troy-Bilt mowers
have oil level switches that will kill the ignition if there's no oil.
2.  Check for spark with a proper spark plug tester.  If the spark gap
looks "crusty" clean or replace the plug.
3.  Disconnect the fuel line between the gas tank and the carb.
4.  Replace it with a short (about 6") length of translucent fuel
line.  Fill the fuel line with fresh gas.  The fuel should fill the
line until the needle valve closes.  At that point, the fuel level
should remain constant and not go down.  If it does go down, the
needle valve and seat might need cleaning or replacement.
5.  Remove the air box (and air filter).  Spray 1 short blast of
carburetor cleaner into the carb.  Just one blast or maybe two, but no
more.
6.  Try to start the engine.  If everything is working, then it should
run for a few seconds and then die.
7.  If you think it's running, then empty the gas tank into 2L soft
drink bottles.  Use a rag on a stick to mop up any remaining water. If
you don't want to do that, make a temporary fuel tank from an inverted
bottle, fuel line and fuel valve for testing.
>
There are all kinds of other things that could go wrong at this point.
Too much for me to explain tonight.
>
I've been watching YouTube videos from:
<https://www.youtube.com/@jcondon1/videos>
<https://www.youtube.com/@Chickanic>
James Condon knows 4 stroke engines, while "Chickanic" knows lawn
equipment.  Start with the more recent videos because both had a
rather long and painful learning curve when they started making
videos.  The videos that are less than about 5 years old are more
organized and useful.
>
So much for short version.
Good luck with the repair.

 As an aside, most of the problems with small engines being stored for
long periods of time can be caused by the fact that much "Gas Station"
gas contains Ethanol. It's worth it to search for "pure gasoline" gas.
https://www.buyrealgas.com/states.html
https://www.pure-gas.org/
 I believe that some airfields that cater to old fashioned propeller
airplanes may also stock it.
 

+1
Ethanol is food for bacteria which make a biofilm goo in all the hard to reach passages and ports.  The extra water from condensation only speeds that process.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971