Good evening,

On this engine, the carb (bowl type, no speed or mixture adjustments)
is allowing gasoline to pass through and fill up the crankcase and air
cleaner housing.

The lawnmower was having issues with stalling a few seconds after
starting. I noted that I could keep it running by continually pressing
the primer bulb; I figured it had an air leak or needed cleaning, so I
decided to rebuild.

I replaced all gaskets, rubber seals, welch plugs, and needle valve &
hinge pin using OEM parts. Cleaned everything with carb cleaner
(aerosol). Reassembled and was still having the stalling problem (but
no gas leak yet). I figured I didn't do a good enough job cleaning the
carb jets and used more solvent and compressed air. Reassembled the
carb again and installed.

Now the gas starts flowing. I disassembled the carb a third time and
verified that none of the seals/gaskets/plugs were missing or
improperly installed. Still experiencing the gas leak.

I'm pretty sure my technique isn't an issue, as I didn't have any
problems after installing the new seals; only after using the
compressed air did the leak begin. I can't tell where the gas is
coming from, but can confirm that it isn't from the bowl itself or the
nozzle extending from the bowl area into the air passage near the
throttle plate.

The lawnmower was purchased in 1999 but has less than 100 hours of use.
It has needed frequent carb cleanings lately. Interestingly, the
engine was built one year prior to the purchase of the lawn mower
(based on engine date code).

Any ideas on what's going on? Thanks.

Andy replies:

If you tested the float valve by lifting the float and noting that
the
flow cut off, then the floats are not closing the float valve.
Couple of possibilities:

1) Floats are leaking or have already filled up and
don't
float anymore
2) Float tab needs to be bent a little more to push
the
float valve a little more

3) Float is binding on the side of the carb bowl for
some
reason. Maybe it got bent or something....

This is not an ususual problem. In my case, once, there was
some crap stuck in the float valve and it couldn't shut proplerly....

A gas leak is NOT due to passageways being clogged. It IS due to
faulty float valve operation, cause that's what the damn thing
does......


Andy in Eureka, Texas

Its your float, it isnt closing completely alowing g s to pass. It might
be dirt in the jet but reality is it isnt stopping the flow when the
bowl is full. Your crankcase oil will need to be changed twice, on the
second change to remove gas run it 5 minutes, the diluted oil will ruin
the motor. A fuel filter would have helped.

m Ransley wrote:
Its your float, it isnt closing completely alowing g s to pass. It might
be dirt in the jet but reality is it isnt stopping the flow when the
bowl is full. Your crankcase oil will need to be changed twice, on the
second change to remove gas run it 5 minutes, the diluted oil will ruin
the motor. A fuel filter would have helped.



If it's a stuck open or leaking float valve please explain how a fuel
filter would have "helped". (Unless it was completely clogged G).

All I can see it doing is making it take a little bit more time for the
tank to drain down to empty.

***********************************

Whilst on the question of small engine carbs, since many of my neighbors
know I'm handy and enjoy helping, I get to fix a few of their mowers and
snowblowers every year.

I've noticed how many carbs have evolved into ones without accessable
fuel adjustments and my curious mind wants to know what the prevailing
motives for this change are. I can think of a couple of reasons:

1. Some sort of emmissions control issue? (I remember near the end of
the era of carbureted car engines the carbs had their idle adjust needle
valves "sealed" with Welsch plugs you had to pry out to get at them.

2. Cheaper to manufacture?

Anything else?

Thanks guys,

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

If it's a stuck open or leaking float valve please explain how a fuel
filter would have "helped". (Unless it was completely clogged G).
---- Jerf

Andy writes:

I'll take this one.... The theory is that some crap may have come
in with the fuel and lodged in the float valve, preventing it from
closing completely ( this happened to me , once )...

A fuel filter in the line may have caught the crap before it
entered the carb. This is a good bet. All the better mowers
have small fuel filters in the line, and one can be bought for
2-3 dollars and added easily if they don't have one....

Remember, most gas can usually have crap in the bottom
after a few years.....

Andy in Eureka, Texas

Andy wrote:

If it's a stuck open or leaking float valve please explain how a fuel
filter would have "helped". (Unless it was completely clogged G).
---- Jerf

Andy writes:

I'll take this one.... The theory is that some crap may have come
in with the fuel and lodged in the float valve, preventing it from
closing completely ( this happened to me , once )...

A fuel filter in the line may have caught the crap before it
entered the carb. This is a good bet. All the better mowers
have small fuel filters in the line, and one can be bought for
2-3 dollars and added easily if they don't have one....

Remember, most gas can usually have crap in the bottom
after a few years.....

Andy in Eureka, Texas



That "thwock" you just heard was me, giving myself a dope slap to the
forehead.

I was focusing on a sunk float and erroneously thought Ransley was
saying that a fuel filter would have somehow mollified the overflow.

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Junk from your can or whatever falls into the gas tank ends up
somewhere, the jet that is supposed to seal off gas with the float can
get a piece of dirt in it not alowing a complete seal. A 50cent fuel
filter can save a motor from being ruined from gas diluted oil.

My neighbor used to lend out his 700$ generator till he got it back
seized. Oil-gas poured out the crankcase when he went to check the oil.
He thought his motor was trash since it would not turn over, when I
turned it over with the spark plug removed gas shot out 15 feet. The
culprit was a piece of dirt not allowing his float valve to seal off
gas. Even being carefull my plastic lawnmower gas can always has junk I
filter out as I fill my equipment, something I hope my new 50 cent fuel
filters will catch. But why don`t all gas power tools come with filters.

My neighbor used to lend out his 700$ generator till he got it back
seized. --- Ramsey

Andy comments:
I had a similar problem with a B&S outboard boat motor
(4 cycle, air cooled, single cylinder)
I crank it every month and run it when it is not being used
regularly, and I went to pull the starter rope and it wouldn't
come.... I figured the engine had seized, or something, and
was puzzled...

I pulled the plug, and found the cylinder had filled with
oil. The piston could not compress it,and it felt real real
real solid, like a seizure.... Well, I pulled it thru a couple
times and put the plug back in, and it cranked fine...

It seems that I had left the motor in a position that allowed
oil to leak around the rings over a month period. I needed to
store the motor in a tilted position so that can't happen....

Just something I ran into than Ransley reminded me of,
and I thought I'd mention it.... Be sure you leave your
motor, or generator, in a position where this won't happen..

Andy in Eureka, Texas