On Fri, 21 Aug 2015 10:27:17 -0400, J Burns
wrote:

On 8/21/15 7:57 AM, Arnie Goetchius wrote:
J Burns wrote:


Does yours backfire when you shut it off?

I'm getting intrigued. The only shutoff solenoid I was familiar with, was on the
Kohler engine of a John Deere riding mower from the late 80s. If it was to
prevent backfiring, I wonder why earlier engines didn't backfire when shut off.

I have a Simplicity from the early 90s with a Kohler engine. The carburetor
looks identical to carburetors with shutoff solenoids, but this carburetor never
had one. It was 20 years old when I got it. For the first year, it would
backfire perhaps ten seconds after I shut it off. For some reason, it hasn't
backfired in a long time. Whatever caused it to backfire, it doesn't need a
solenoid to prevent it.


I never had a backfire before or after installing the shutoff.

Strictly speaking, backfiring in the exhaust is afterfiring. Gas
self-ignites at about 500 F. One would think that when the ignition was
cut with the engine not under a load (small gas/air charge), each little
charge would ignite as it left the exhaust valve, without much noise,
like a blowtorch.

Maybe it doesn't ignite because it mixes with the exhaust in the
muffler, diluting it too much to explode. Maybe after ten seconds, the
cooler oxygen and gasoline settle to the bottom, reaching the
concentration necessary to explode.

I don't think they are talking about exhaust backfire - if so the
solenoid won't prevent that. I think they are talking about after-run
- or "deiseling" where the engine continues to "run" after the
ignition is shut off. This hapens if the engine can still get fuel and
there is a hot spot or other self-ignition point in the cyl. The
solenoid shuts off all fuel so it cannot continue to fire. Letting
the engine idle right down with the throttle fully closed does the
same thing by restricting air instead of fuel

How did afterfiring become a problem? The EPA! It used to be routine
to throttle down all the way before cutting the ignition, but for
decades, manuals have said not to throttle down. I think I see why.
It's hard to design an gas engine to burn clean at an idle. If engine
companies said not to idle, they could give the EPA emissions figures
that didn't include idle speeds.

If the ignition is cut at an engine's working speed of 3600 rpm, the
inertia of the engine will probably pump 16 times more air/fuel mixture
into the muffler than if the operator had first throttled down to 900
rpm BAM!

The reasons to run a mower at maximum rpms would be for blade power to
cut heavy growth, for wind to prevent clogging, and for ground speed to
race through a job. I don't have a tach, but I suppose I've generally
run at half speed for some time because full speed isn't usually
required. A slower engine means less noise, less dust, less fuel, and
less slowing for turns. Shutting off at half speed means much less
fuel/air in the muffler. That would explain why I haven't heard a bang
in a long time.

I believe I will now ignore the manual and throttle down all the way
before switching the ignition off. It couldn't cause much pollution
unless I idled extensively. What kind of guy idles a mower extensively?
The kind who takes cigarette breaks! He goes next door for a moment,
and all the children die of terrible diseases, and statisticians
attribute it to third-hand cigarette smoke, the smell on his clothes.
In fact, they died because they were downwind from his idling mower!

I'm starting to think consumers were saddled with expensive,
trouble-prone shutoff solenoids simply to pass EPA requirements that are
meaningless in the real world. It would be great if a solenoid could
prevent trouble from a leaky float valve, though!

On Fri, 21 Aug 2015 10:45:06 -0700, Oren wrote:

On 21 Aug 2015 17:35:51 GMT, notbob wrote:

On 2015-08-21, J Burns wrote:

cause afterfire if shut off when idled down.

WTF is "afterlife"? Is that a new term for "dieseling"?

https://en.wikipedia.org/wiki/Dieseling

nb

G "afterfire" (back-fire) is different from "afterlife"

https://en.wikipedia.org/wiki/Afterlife

"Back-fire is an unintended explosion produced in a vehicle's engine."

Technically not "in" the engine, but either in the exhaust or intake,
depending on what kind of "backfire" you are talking about.

On 8/21/15 9:53 PM, wrote:

I don't think they are talking about exhaust backfire - if so the
solenoid won't prevent that. I think they are talking about after-run
- or "deiseling" where the engine continues to "run" after the
ignition is shut off. This hapens if the engine can still get fuel and
there is a hot spot or other self-ignition point in the cyl. The
solenoid shuts off all fuel so it cannot continue to fire. Letting
the engine idle right down with the throttle fully closed does the
same thing by restricting air instead of fuel

For me, dieseling has always happened with the my foot off the gas. The
first was in 1969, a big pickup that was about 20 years old. The others
were an F-150 and at least two cars made in the 1970s.

All of them idled with the throttle somewhat open. The old pickup needed
an overhaul. The idle had been adjusted to keep it from stalling. The
vehicles of the 70s used retarded timing and a partly open throttle to
reduce emissions at idle.

In riding mowers, we're talking about a single bang in the muffler. It
would happen to me after I'd dismounted. I learned to wait for the bang
before I leaned over to shut off the fuel, so my ear wouldn't be near
the muffler.

I believe the big reason throttling down helps is that a slower-turning
engine won't pump so much fuel into the muffler during the spin-down,
after the ignition is switched off.

I believe the instructions to shut off a mower at full speed came from
the observation that landscapers who cut the throttle before cutting the
ignition needed more overhauls. I think what hurts is not cutting the
throttle but failing to give the engine time to cool with enough RPMs to
blow plenty of air. Airplane engines are cooled at a fast idle so the
propeller will fan them. Shutting off a hot engine would be bad whether
or not the pilot cut the throttle first.

On 8/21/15 1:35 PM, notbob wrote:
On 2015-08-21, J Burns wrote:

cause afterfire if shut off when idled down.

WTF is "afterlife"? Is that a new term for "dieseling"?

https://en.wikipedia.org/wiki/Dieseling

nb

Harriet Hilliard's (what a dish!) son Eric had a DC-3 because he didn't
like dieseling around the country on a bus. He and his band took a
horrifying trip to the afterlife just before America rang in 1986.

Somebody with influence had newspapers across the country publish a
specious front-page story saying federal investigators blamed
Eric. Investigators immediately responded that this was a lie. Editors
across the country hid the rebuttal inside, with no headline. The
public ignored it.

The summary of the NTSB report implied that the fire was caused by a
gasoline heater installed by a piano player known as The Killer. The
report itself contradicts this. The heater was functioning perfectly.
The gasoline fire erupted after the crash. The passengers were already
dead. The fire that had killed them did not involve gasoline. It
started at floor level at the rear of the passenger cabin. It did not
say how it started. The baggage was in another compartment.

The pilot had gone back there when smoke was reported, pulled an
extinguisher from the bulkhead, pulled the pin on the extinguisher, put
it back on the bulkhead without using it, and returned to the cockpit.
The plane dropped molten aluminum for half a mile leading to the crash
site. It's very unusual for a plane to burn that hot.

If the pilot realized an extinguisher would be useless, and the fire was
intense enough to melt aluminum, what explanation could there be except
that the aluminum of the airplane was itself on fire? It takes thermite
to ignite aluminum. Investigators analyzed samples of the aluminum near
the burn. That could have told them what kind of thermite was used.
Presumably, the NTSB was ordered not to state the cause of the fire for
the sake of the FBI investigation. Was Ed Meese really going to
prosecute the mass murderers? Hah!

Statements Eric's brother David made, indicate that the FBI had told him
of evidence against two women. When one of them barged in on the funeral
drunk, he walked up to her and said, "Murderess!" She then knocked
Eric's daughter to the ground with several blows before the
grief-stricken could pull her off.

Eric was the mysterious dark-haired man in "Delta Dawn," written by her
brother, a close friend of Eric's since the three were children. More
than ten years after the murder, she revealed that when she was 14 and
he 16, a 27-year-old had expressed such intense jealousy that at first
she thought he was joking. When she realized he was obsessed, she was
afraid to be near him, but she kept quiet because she loved his wife and
daughters, and she was afraid people would think she'd invited his
advances. Others had spoken of the obsession he confided over the years.
His intensity scared them, too.

At the time of the murder, he was probably a suspect in an attempt to
murder Eric and his band 3 months earlier. It blew right past the
public because education in this country is such a mess that one can get
a diploma without knowing the difference between backfiring and afterfiring.

Eric had offered Marty Stuart a fight from Memphis to the Mellencamp
camp. The plane sat idling, but Stuart didn't show up. On the takeoff
roll, both engines backfired and quit.

How could two completely independent engines quit at the same time? If
they hadn't waited for Stuart, the engines could have quit after the
point of no return. That would have been fatal.

A DC-3 can't after-fire because the exhaust is wide open. Insufficient
fuel is the only thing that can cause it to backfire. It's second nature
for a pilot to shove the mixture controls to full rich for takeoff. If
somehow they'd forgotten, it would have been obvious as soon as they
shoved the throttles forward, not halfway down the runway.

It couldn't have been pump failure because on takeoff, each engine was
fed by an electric pump in parallel with a mechanical pump. They must
have run out of gas, as if the airport hadn't filled the tanks and the
gauges were faulty. That couldn't be it. Each engine drew from its own
tank. They couldn't have run dry at the same time unless a saboteur
with a fuel truck had sucked all the fuel out, put in a measured amount,
and tampered with the gauges.

Who even knew he was in Memphis? He'd been invited on short notice.
He'd been deceived. He'd brought his band to record, but all they did
was stand around the studio for two days. Of those in a position to
invite him, the only one who even knew him was the man obsessed with
Delta Dawn.

That incident made me conscious of the distinction between backfiring
and after-firing. Accusing the culprit would be as outrageous as saying
O J Simpson cut two people's throats, but F Degraff has posted three
videos on youtube. His father was David's classmate at Hollywood High.

Arnie Goetchius wrote:
J Burns wrote:
On 6/8/15 3:04 PM, Arnie Goetchius wrote:
I took the spark plug out and the starter turned the engine over with no
problem. Replaced with new spark plug. Also noticed what appeared to be
an excessive amount of oil in crank case so drained oil and replaced
with 42 oz of 30 W.(Briggs & Stratton 287707-1224) Started right up.
That was Sunday. Started several times during the day, all okay.

Proceeded to mow the lawn today with no problem. The acid test will be
if the starter will turn the engine over this weekend after having not
been run for 5 days. Fingers crossed!!

On motorcycles with horizontally opposed engines, I sometimes couldn't kick them
over because of hydrostatic lock. If the bike was left long enough on the side
stand, oil could seep past the rings into the cylinder. I'd remove the plug,
kick it over to blow the oil out, put the plug back in, and start.

If you had too much oil, you may have had hydrostatic lock when you left it more
than a day.

It turned out that I did have hydrostatic lock but from the gasoline, not the
oil. On the bottom of carburetor, there is a switch that is connected to the
ignition switch. When you turn off the engine, it also supposed to operate the
carburetor switch so that no more gas enters the carburetor. However, that
appears to be broken because there is a lot of gas left in the cylinder and I
cant turn the engine over after a week.

To turn the engine over with the starter, I had to remove the spark plug first.
When I turned the engine over with spark plug out, it yielded a lot of gas
coming out of the cylinder so I figured gas was leaking into the cylinder after
I turned the engine off. So I added a manual gas shutoff valve to the gas line
and turn that off to shut the engine down when Im done mowing. After the
engine stops, I also turn off the ignition. I let it sit for a week and just
started it up today with no problem.

I think I have solved the problem now but I thought so before so fingers
crossed!! Thanks for your tip on the hydrostatic lock.

Lost my unit after it failed shutoff and gas entered oil. Ran for a bit
after I changed oil.

Greg

On 8/24/15 3:54 AM, gregz wrote:
Lost my unit after it failed shutoff and gas entered oil. Ran for a bit
after I changed oil.

Greg

Did gas seep past the manual shutoff?

More than ten years ago, a neighbor asked me to start his chipper. I
pulled the spark plug, maybe because of hydrostatic lock. Before long, I
discovered that the oil level was way too high and it didn't smell or
feel right.

I guess that was a single incident, where he stored it without shutting
off the fuel. If fuel had repeatedly leaked past the shutoff and not
been noticed, I guess the engine would have been damaged.

I love ball valves. (Is that what they're called?) You can see if
they're off, and I don't remember a leaky one.

J Burns wrote:
On 8/24/15 3:54 AM, gregz wrote:
Lost my unit after it failed shutoff and gas entered oil. Ran for a bit
after I changed oil.

Greg

Did gas seep past the manual shutoff?

More than ten years ago, a neighbor asked me to start his chipper. I pulled the
spark plug, maybe because of hydrostatic lock. Before long, I discovered that
the oil level was way too high and it didn't smell or feel right.

I guess that was a single incident, where he stored it without shutting off the
fuel. If fuel had repeatedly leaked past the shutoff and not been noticed, I
guess the engine would have been damaged.

I love ball valves. (Is that what they're called?) You can see if they're off,
and I don't remember a leaky one.

This is what I use. Would you call that a "ball valve"?

http://ecx.images-amazon.com/images/...XL._SY300_.jpg

On 8/24/15 10:31 AM, Arnie Goetchius wrote:
J Burns wrote:
On 8/24/15 3:54 AM, gregz wrote:
Lost my unit after it failed shutoff and gas entered oil. Ran for a bit
after I changed oil.

Greg

Did gas seep past the manual shutoff?

More than ten years ago, a neighbor asked me to start his chipper. I pulled the
spark plug, maybe because of hydrostatic lock. Before long, I discovered that
the oil level was way too high and it didn't smell or feel right.

I guess that was a single incident, where he stored it without shutting off the
fuel. If fuel had repeatedly leaked past the shutoff and not been noticed, I
guess the engine would have been damaged.

I love ball valves. (Is that what they're called?) You can see if they're off,
and I don't remember a leaky one.

This is what I use. Would you call that a "ball valve"?

http://ecx.images-amazon.com/images/...XL._SY300_.jpg

It looks like the one I installed. I'm absent-minded. I want to know at
a glance!

"J Burns" wrote in message ...


Pull the plug outa yer arse and put it in the machine.

J Burns wrote:
On 8/24/15 3:54 AM, gregz wrote:
Lost my unit after it failed shutoff and gas entered oil. Ran for a bit
after I changed oil.

Greg

Did gas seep past the manual shutoff?


Guess so. I also have a generator that tends to stick open.

Greg

More than ten years ago, a neighbor asked me to start his chipper. I
pulled the spark plug, maybe because of hydrostatic lock. Before long, I
discovered that the oil level was way too high and it didn't smell or feel right.

I guess that was a single incident, where he stored it without shutting
off the fuel. If fuel had repeatedly leaked past the shutoff and not
been noticed, I guess the engine would have been damaged.

I love ball valves. (Is that what they're called?) You can see if
they're off, and I don't remember a leaky one.

gregz wrote:
J Burns wrote:
On 8/24/15 3:54 AM, gregz wrote:
Lost my unit after it failed shutoff and gas entered oil. Ran for a bit
after I changed oil.

Greg

Did gas seep past the manual shutoff?


Guess so. I also have a generator that tends to stick open.

Greg


I dont think the lawnmower has a shutoff valve. Just that solenoid that's
supposed to work. My generator has both, so I can shut It back off when it
drips to ground. I hit the solenoid and it closes. Must not close when I
shutdown generator and let I sit.

Greg

More than ten years ago, a neighbor asked me to start his chipper. I
pulled the spark plug, maybe because of hydrostatic lock. Before long, I
discovered that the oil level was way too high and it didn't smell or feel right.

I guess that was a single incident, where he stored it without shutting
off the fuel. If fuel had repeatedly leaked past the shutoff and not
been noticed, I guess the engine would have been damaged.

I love ball valves. (Is that what they're called?) You can see if
they're off, and I don't remember a leaky one.

Since small particles of junk in the fuel can cause a carburetor to fail, every gas engine should have a fuel filter.
In-line filters for small engines can be had for a couple bucks and can be installed by any trunk monkey of average intelligence.

On 8/25/2015 4:12 AM, Rowan Pope wrote:
Since small particles of junk in the fuel can cause a carburetor to
fail, every gas engine should have a fuel filter.
In-line filters for small engines can be had for a couple bucks and can
be installed by any trunk monkey of average intelligence.



My two stroke snow blower kept clogging carb,
and finally I gathered up all my lower than
average intelligence, and installed inline fuel
filter. That helped, a lot. I was then able to
go back to eating bannannas and swinging from
trees.

--
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

"Rowan Pope" wrote in message
...
Since small particles of junk in the fuel can cause a carburetor to fail,
every gas engine should have a fuel filter.
In-line filters for small engines can be had for a couple bucks and can be
installed by any trunk monkey of average intelligence.



I have a chain saw that has a filter at the end of the pickup tube for the
gas. It broke off at the end of the tube. The carborator cloged up twice
before I found that filter off the tube.