Briggs & Stratton 18.5 HP Carburator problem

bertsmobile1 said:

Almost but not quite.
The solenoid jambs a plug into the end of the main jet so even if the float bowl is full of fuel, none can get into the engine.
It is to prevent the engine pumping out unburned fuel between the time the spark stops and the engine stops rotating.
Apparently this will prevent the world as we know ceasing to exist.
Now think of it, around 50,000 mowers in the USA with an average capacity of 500 cc.
The engine does around 5 revolutions before it stops so that is 0.5 L x 5 x 50,000 = 125,000 liters of unburned fuel vapour ( about 2000 gallons) going into the atmosphere every week .
Oh lord save us from our sins
Or the same amount as 10 jets with 4 engines taking off .
Only they do it 10 times a day
Like a lawnmower is really gong to make a difference.

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Bert, I do always appreciate your somewhat alternate view on these matters...
I was of the impression that the solenoid prevented fuel from entering the engine, passing thru it unburned into the muffler,
where it would ignite in a rather annoying POP !

Roger B said:

Boo-Boo,

You're too good to me.. What did I ever do to earn your undying help and assistance?

Hey! Bert-Man tells me there is a "front (or back) porch" place for generalizations and wanderings.. (Which we seem to have a tendency to do - well me anyway..) Maybe we could generate a new thread there and attract some additional contributors... Wha'Cha think about that???

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I came ... I saw ....I posted .... Probably will get bounced off the thread or site for my "brash" remarks !!!
Daffodils ... pansy's ...pansies .... poofballs !!! Ha,Ha, Ha, .............. :laughing: ..:laughing: ..:laughing:..:cool2:

Ronno6 said:

Bert, I do always appreciate your somewhat alternate view on these matters...
I was of the impression that the solenoid prevented fuel from entering the engine, passing thru it unburned into the muffler,
where it would ignite in a rather annoying POP !

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They called it an ant-afterfire solenoid because of what you said.
However they were compulsory in Cal .
I buy a lot of engines from the USA and the ones marked "Illegal for use in Cal" do not have the solenoid so that puts pay to that bull dust dosent it.
About 3/4 of the mowers sold down here do not have the solenoid fitted.
However they are compulsory in clean green ACT .

bertsmobile1 said:

They called it an ant-afterfire solenoid because of what you said.

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I can say from personal experience that they do prevent that annoying afterfire.............

Ronno6 said:

I can say from personal experience that they do prevent that annoying afterfire.............

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And so does throttleing down before you shut down which is what you were told to do before they were fitted or turning off the fuel at the tap and starving the engine off.
They are an EPA regulation but to make them "acceptable" to Joe Public they pretend there is a benefit to the user.
Down here they go for $ 150 to $ 75 ( Aus) and at that price are more expensive than some of the carbs they sit on.
Thus most home owners will just rip the !&@#$%@#$!# thing off when they cause troubles.

bertsmobile1 said:

And so does throttleing down before you shut down which is what you were told to do before they were fitted or turning off the fuel at the tap and starving the engine off.
They are an EPA regulation but to make them "acceptable" to Joe Public they pretend there is a benefit to the user.
Down here they go for $ 150 to $ 75 ( Aus) and at that price are more expensive than some of the carbs they sit on.
Thus most home owners will just rip the !&@#$%@#$!# thing off when they cause troubles.

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I'm sorry, but I must disagree.
Not only would I throttle down to idle, but I would also shut off a pet cock which I installed in the fuel line.
After closing the fuel valve, I would idle the engine a moment to tale pressure off the needle/seat inlet.
I would still get the annoying afterfire even after that procedure.

Nobody ever "told" me to slow to idle before turning off the ignition...it is just common sense.........

Ronno6 said:

I'm sorry, but I must disagree.
Not only would I throttle down to idle, but I would also shut off a pet cock which I installed in the fuel line.
After closing the fuel valve, I would idle the engine a moment to tale pressure off the needle/seat inlet.
I would still get the annoying afterfire even after that procedure.

Nobody ever "told" me to slow to idle before turning off the ignition...it is just common sense.........

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Sorry Ronno
I have to agree with bert...... I have 2 mowers, .. both with the 17.5 HP Briggs engines each with the Nikki carb.
each has the solenoid... which operates as they should... yet on occasion ..... whether I idle down for a short period or throttle -up while shutting-down, I get the shot-gun pop which puts the neighbors cat ..up the tree !! I 'm thinking the solenoid is actually there to prevent a hydro-lock of the engine in case the needle valve becomes stuck in the open position and allows fuel to enter the engine.. in any case if & when mine fail ... they will NOT be replaced ..Boobala

Boobala said:

Sorry Ronno
I have to agree with bert...... I have 2 mowers, .. both with the 17.5 HP Briggs engines each with the Nikki carb.
each has the solenoid... which operates as they should... yet on occasion ..... whether I idle down for a short period or throttle -up while shutting-down, I get the shot-gun pop which puts the neighbors cat ..up the tree !! I 'm thinking the solenoid is actually there to prevent a hydro-lock of the engine in case the needle valve becomes stuck in the open position and allows fuel to enter the engine.. in any case if & when mine fail ... they will NOT be replaced ..Boobala

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No need to apologize.
Our experiences differ.
YMMV...........

The thing is Boobala the solenoid will not stop a hydrolock because it cannot prevent fuel overflow through the carb bowl vent into the venturi if the float valve sticks open. Most of the time it will stop the afterfire bang, but not all the time. Kohler says shut there engines off at full throttle because the design of the carb prevents the solenoid from shutting off the fuel flow on the idle circuit, only the high speed jet.

I have a customer that has a Toro that didn't matter what you did would still afterfire. A few years ago I had to install a new engine on that mower due to a valve dropping into the cylinder while it was running. Started the new engine up, and got it to operating temp, let it idle for about 30 seconds, and shut it off to the nice little bang. the only thing that wasn't replaced with the engine swap was I had to reuse the muffler. In this case the muffler is the problem that is allowing the afterfire.