I have an old Craftsman 6HP vertical shaft chipper/shredder that is giving me
trouble. The engine idles great, but at any higher speed, runs really rich,
making black smoke, and even spitting gas out the carb if I take the air cleaner
off. It does not rev properly in the process, except when it first starts or as
it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have replaced it
a couple years ago when I acquired this unit used. The gas valve it operates
seems to operate also. If I blow into the fuel inlet, no air passes until I push
up on the needle that opens the fuel flow. I even tried installing a layer of
plastic from a bag "outside" of the diaphram (between it and the cover) to
eliminate the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher speeds are all
super rich?

The idle needle adjustment works properly. The high speed needle adjustment
seems to have no effect, other than if I remove it completely, at which point
the engine will quickly speed up like it should work for a few seconds before it
then dies.

Any ideas? Is there something I haven't thought of that could be repaired on
this carb/engine?

Oren wrote:
On Fri, 13 May 2011 15:32:42 -0700, "Bob F"
wrote:

I have an old Craftsman 6HP vertical shaft chipper/shredder that is giving me
trouble. The engine idles great, but at any higher speed, runs really rich,
making black smoke, and even spitting gas out the carb if I take the air cleaner
off. It does not rev properly in the process, except when it first starts or as
it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have replaced it
a couple years ago when I acquired this unit used. The gas valve it operates
seems to operate also. If I blow into the fuel inlet, no air passes until I push
up on the needle that opens the fuel flow. I even tried installing a layer of
plastic from a bag "outside" of the diaphram (between it and the cover) to
eliminate the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher speeds are all
super rich?

The idle needle adjustment works properly. The high speed needle adjustment
seems to have no effect, other than if I remove it completely, at which point
the engine will quickly speed up like it should work for a few seconds before it
then dies.

Any ideas? Is there something I haven't thought of that could be repaired on
this carb/engine?


I would examine the muffler for a clog. Does this mower have a spark
arrester? Clean that also.

...then maybe valve seats

I sometimes wonder about old engines and E10 gas. Gas companies no longer
tell anyone that almost all regular gas in the US contains ethanol. I see
these little bottles of E10 fuel additives in stores now for small engines.
I wonder if any how much damage is being done to old small engines.

--
Enjoy Life... Nad R (Garden in zone 5a Michigan)

On May 13, 5:32*pm, "Bob F" wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is giving me
trouble. The engine idles great, but at any higher speed, runs really rich,
making black smoke, and even spitting gas out the carb if I take the air cleaner
off. It does not rev properly in the process, except when it first starts or as
it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have replaced it
a couple years ago when I acquired this unit used. The gas valve it operates
seems to operate also. If I blow into the fuel inlet, no air passes until I push
up on the needle that opens the fuel flow. I even tried installing a layer of
plastic from a bag "outside" of the diaphram (between it and the cover) to
eliminate the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher speeds are all
super rich?

The idle needle adjustment works properly. The high speed needle adjustment
seems to have no effect, other than if I remove it completely, at which point
the engine will quickly speed up like it should work for a few seconds before it
then dies.

Any ideas? Is there something I haven't thought of that could be repaired on
this carb/engine?

It seems fairly obvious that fuel is bypassing the high-speed jet.
Maybe the needle has worn down. If gas was not bypassing the high-
speed jet, with the jet fully screwed in, the engine would die at high
speeds, not run rich and belch black smoke. I would look at the
highspeed jet needle and its valve seat and see if either are worn.

hr(bob) wrote:
On May 13, 5:32 pm, "Bob F" wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is
giving me trouble. The engine idles great, but at any higher speed,
runs really rich, making black smoke, and even spitting gas out the
carb if I take the air cleaner off. It does not rev properly in the
process, except when it first starts or as it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have
replaced it a couple years ago when I acquired this unit used. The
gas valve it operates seems to operate also. If I blow into the fuel
inlet, no air passes until I push up on the needle that opens the
fuel flow. I even tried installing a layer of plastic from a bag
"outside" of the diaphram (between it and the cover) to eliminate
the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher
speeds are all super rich?

The idle needle adjustment works properly. The high speed needle
adjustment seems to have no effect, other than if I remove it
completely, at which point the engine will quickly speed up like it
should work for a few seconds before it then dies.

Any ideas? Is there something I haven't thought of that could be
repaired on this carb/engine?

It seems fairly obvious that fuel is bypassing the high-speed jet.
Maybe the needle has worn down. If gas was not bypassing the high-
speed jet, with the jet fully screwed in, the engine would die at high
speeds, not run rich and belch black smoke. I would look at the
highspeed jet needle and its valve seat and see if either are worn.

Excellent ideas. Thanks for your help.

On May 13, 11:32*pm, "Bob F" wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is giving me
trouble. The engine idles great, but at any higher speed, runs really rich,
making black smoke, and even spitting gas out the carb if I take the air cleaner
off. It does not rev properly in the process, except when it first starts or as
it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have replaced it
a couple years ago when I acquired this unit used. The gas valve it operates
seems to operate also. If I blow into the fuel inlet, no air passes until I push
up on the needle that opens the fuel flow. I even tried installing a layer of
plastic from a bag "outside" of the diaphram (between it and the cover) to
eliminate the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher speeds are all
super rich?

The idle needle adjustment works properly. The high speed needle adjustment
seems to have no effect, other than if I remove it completely, at which point
the engine will quickly speed up like it should work for a few seconds before it
then dies.

Any ideas? Is there something I haven't thought of that could be repaired on
this carb/engine?

Air cleaner choked?

On May 13, 5:32*pm, "Bob F" wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is giving me
trouble. The engine idles great, but at any higher speed, runs really rich,
making black smoke, and even spitting gas out the carb if I take the air cleaner
off. It does not rev properly in the process, except when it first starts or as
it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have replaced it
a couple years ago when I acquired this unit used. The gas valve it operates
seems to operate also. If I blow into the fuel inlet, no air passes until I push
up on the needle that opens the fuel flow. I even tried installing a layer of
plastic from a bag "outside" of the diaphram (between it and the cover) to
eliminate the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher speeds are all
super rich?

The idle needle adjustment works properly. The high speed needle adjustment
seems to have no effect, other than if I remove it completely, at which point
the engine will quickly speed up like it should work for a few seconds before it
then dies.

Any ideas? Is there something I haven't thought of that could be repaired on
this carb/engine?

The float could be stuck open. But If so you would have gas in the
oil. If you do, gas in oil can thin it and ruin the motor. but gas
pouring out the carb is likely the float. Does choke stay open, I
would not run it till you go over everything and change the oil. How
is you oil level now, if its up its the float.

Bob F wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is
giving me trouble. The engine idles great, but at any higher speed,
runs really rich, making black smoke, and even spitting gas out the
carb if I take the air cleaner off. It does not rev properly in the
process, except when it first starts or as it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have
replaced it a couple years ago when I acquired this unit used. The
gas valve it operates seems to operate also. If I blow into the fuel
inlet, no air passes until I push up on the needle that opens the
fuel flow. I even tried installing a layer of plastic from a bag
"outside" of the diaphram (between it and the cover) to eliminate the
possibility of any leaks through the diaphram, with no effect.
Would a bad diaphram allow the idle to work great, while higher
speeds are all super rich?

The idle needle adjustment works properly. The high speed needle
adjustment seems to have no effect, other than if I remove it
completely, at which point the engine will quickly speed up like it
should work for a few seconds before it then dies.

Any ideas? Is there something I haven't thought of that could be
repaired on this carb/engine?

Thanks for all the suggestions folks. As one of the early responders said, it
turned out to be a problem with the high speed jet. An internal "cap" was
missing, which allowed gas to bypass the high speed adjustment needle. I had to
pay $11 for a carb kit that had the 3/8" aluminum dome shaped cap in it.
Replaced the cap, and it works perfectly now.

On May 14, 8:22*pm, "Bob F" wrote:
Bob F wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is
giving me trouble. The engine idles great, but at any higher speed,
runs really rich, making black smoke, and even spitting gas out the
carb if I take the air cleaner off. It does not rev properly in the
process, except when it first starts or as it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have
replaced it a couple years ago when I acquired this unit used. The
gas valve it operates seems to operate also. If I blow into the fuel
inlet, no air passes until I push up on the needle that opens the
fuel flow. I even tried installing a layer of plastic from a bag
"outside" of the diaphram (between it and the cover) to eliminate the
possibility of any leaks through the diaphram, with no effect.
Would a bad diaphram allow the idle to work great, while higher
speeds are all super rich?

The idle needle adjustment works properly. The high speed needle
adjustment seems to have no effect, other than if I remove it
completely, at which point the engine will quickly speed up like it
should work for a few seconds before it then dies.

Any ideas? Is there something I haven't thought of that could be
repaired on this carb/engine?

Thanks for all the suggestions folks. As one of the early responders said, it
turned out to be a problem with the high speed jet. An internal "cap" was
missing, which allowed gas to bypass the high speed adjustment needle. I had to
pay $11 for a carb kit that had the 3/8" aluminum dome shaped cap in it.
Replaced the cap, and it works perfectly now.- Hide quoted text -

- Show quoted text -

Any idea what happened to the cap, did it get sucked into the
engine??? Is it flimsy enough that the engine just ate it up? Thanks
for the credit for ponting to the high-speed jet.

hr(bob) wrote:
On May 14, 8:22 pm, "Bob F" wrote:
Bob F wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is
giving me trouble. The engine idles great, but at any higher speed,
runs really rich, making black smoke, and even spitting gas out the
carb if I take the air cleaner off. It does not rev properly in the
process, except when it first starts or as it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have
replaced it a couple years ago when I acquired this unit used. The
gas valve it operates seems to operate also. If I blow into the fuel
inlet, no air passes until I push up on the needle that opens the
fuel flow. I even tried installing a layer of plastic from a bag
"outside" of the diaphram (between it and the cover) to eliminate
the possibility of any leaks through the diaphram, with no effect.
Would a bad diaphram allow the idle to work great, while higher
speeds are all super rich?

The idle needle adjustment works properly. The high speed needle
adjustment seems to have no effect, other than if I remove it
completely, at which point the engine will quickly speed up like it
should work for a few seconds before it then dies.

Any ideas? Is there something I haven't thought of that could be
repaired on this carb/engine?

Thanks for all the suggestions folks. As one of the early responders
said, it turned out to be a problem with the high speed jet. An
internal "cap" was missing, which allowed gas to bypass the high
speed adjustment needle. I had to pay $11 for a carb kit that had
the 3/8" aluminum dome shaped cap in it. Replaced the cap, and it
works perfectly now.- Hide quoted text -

- Show quoted text -

Any idea what happened to the cap, did it get sucked into the
engine??? Is it flimsy enough that the engine just ate it up? Thanks
for the credit for ponting to the high-speed jet.

There would have been no path by which it could have gotten into the engine. I
imagine it dropped out when I was checking the diaphram, and I just missed it. I
guess I will never know for sure.

hr(bob) wrote:
On May 14, 8:22 pm, "Bob F" wrote:
Bob F wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is
giving me trouble. The engine idles great, but at any higher speed,
runs really rich, making black smoke, and even spitting gas out the
carb if I take the air cleaner off. It does not rev properly in the
process, except when it first starts or as it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have
replaced it a couple years ago when I acquired this unit used. The
gas valve it operates seems to operate also. If I blow into the fuel
inlet, no air passes until I push up on the needle that opens the
fuel flow. I even tried installing a layer of plastic from a bag
"outside" of the diaphram (between it and the cover) to eliminate
the possibility of any leaks through the diaphram, with no effect.
Would a bad diaphram allow the idle to work great, while higher
speeds are all super rich?

The idle needle adjustment works properly. The high speed needle
adjustment seems to have no effect, other than if I remove it
completely, at which point the engine will quickly speed up like it
should work for a few seconds before it then dies.

Any ideas? Is there something I haven't thought of that could be
repaired on this carb/engine?

Thanks for all the suggestions folks. As one of the early responders
said, it turned out to be a problem with the high speed jet. An
internal "cap" was missing, which allowed gas to bypass the high
speed adjustment needle. I had to pay $11 for a carb kit that had
the 3/8" aluminum dome shaped cap in it. Replaced the cap, and it
works perfectly now.- Hide quoted text -

- Show quoted text -

Any idea what happened to the cap, did it get sucked into the
engine??? Is it flimsy enough that the engine just ate it up? Thanks
for the credit for ponting to the high-speed jet.

I forgot to say - You are very welcome.

On May 15, 11:37*am, "Bob F" wrote:
hr(bob) wrote:
On May 14, 8:22 pm, "Bob F" wrote:
Bob F wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is
giving me trouble. The engine idles great, but at any higher speed,
runs really rich, making black smoke, and even spitting gas out the
carb if I take the air cleaner off. It does not rev properly in the
process, except when it first starts or as it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have
replaced it a couple years ago when I acquired this unit used. The
gas valve it operates seems to operate also. If I blow into the fuel
inlet, no air passes until I push up on the needle that opens the
fuel flow. I even tried installing a layer of plastic from a bag
"outside" of the diaphram (between it and the cover) to eliminate
the possibility of any leaks through the diaphram, with no effect.
Would a bad diaphram allow the idle to work great, while higher
speeds are all super rich?

The idle needle adjustment works properly. The high speed needle
adjustment seems to have no effect, other than if I remove it
completely, at which point the engine will quickly speed up like it
should work for a few seconds before it then dies.

Any ideas? Is there something I haven't thought of that could be
repaired on this carb/engine?

Thanks for all the suggestions folks. As one of the early responders
said, it turned out to be a problem with the high speed jet. An
internal "cap" was missing, which allowed gas to bypass the high
speed adjustment needle. I had to pay $11 for a carb kit that had
the 3/8" aluminum dome shaped cap in it. Replaced the cap, and it
works perfectly now.- Hide quoted text -

- Show quoted text -

Any idea what happened to the cap, did it get sucked into the
engine??? *Is it flimsy enough that the engine just ate it up? *Thanks
for the credit for ponting to the high-speed jet.

I forgot to say - You are very welcome.

One other possibility: clogged cooling fins. That's what was causing
a friends mower to over heat and die when operatied at "normal"
throttle settings. It took 4 trips to the repair shop to have their
untrained drop-outs fix it. Eventually, the owner discovered the real
problem.

ransley wrote:
On May 13, 5:32 pm, "Bob F" wrote:
I have an old Craftsman 6HP vertical shaft chipper/shredder that is giving me
trouble. The engine idles great, but at any higher speed, runs really rich,
making black smoke, and even spitting gas out the carb if I take the air cleaner
off. It does not rev properly in the process, except when it first starts or as
it runs out of gas.

The diaphram in the carb looks excellent. It looks new. I might have replaced it
a couple years ago when I acquired this unit used. The gas valve it operates
seems to operate also. If I blow into the fuel inlet, no air passes until I push
up on the needle that opens the fuel flow. I even tried installing a layer of
plastic from a bag "outside" of the diaphram (between it and the cover) to
eliminate the possibility of any leaks through the diaphram, with no effect.

Would a bad diaphram allow the idle to work great, while higher speeds are all
super rich?

The idle needle adjustment works properly. The high speed needle adjustment
seems to have no effect, other than if I remove it completely, at which point
the engine will quickly speed up like it should work for a few seconds before it
then dies.

Any ideas? Is there something I haven't thought of that could be repaired on
this carb/engine?

The float could be stuck open. But If so you would have gas in the
oil. If you do, gas in oil can thin it and ruin the motor. but gas
pouring out the carb is likely the float. Does choke stay open, I
would not run it till you go over everything and change the oil. How
is you oil level now, if its up its the float.


That would be a Tecumseh engine, not a B&S.

-Bob

g'day bob,

my policy don't look a teh diaphram replace it, once you pull it out
and it dries that can make it worse.

black smoke usually means running rich, look for badly seviced air
cleaner element, replace if it is a paper cartridge type. replace
diaphram, the tune should not alter without human imput to move the
adjustment jet screw, also the spark plug should be in best condition.

for me i'd be hinking something is wrong with the air cleaner setup,
it has become fouled and is acting like a choke causing the machine to
run rich.

keep us informed

we still get unleaded fuel over here that is ideal for low compression
garden equipment engies would not suggest using E10 or other grades of
unleaded fuel in these engines, my mower engine 20 odd years old and
going strong.

On Fri, 13 May 2011 15:32:42 -0700, "Bob F"
wrote:
snipped
--

Matthew 25:13 KJV
"Watch therefore, for ye know neither
the day nor the hour wherein the Son
of man cometh"

Mark 13:33 "Take ye heed, watch and pray:
for ye know not when the time is".

and also: Isaiah 38:1&17-18 KJV

1: Thus saith the Lord, set thine house in order: for thou shalt die and not live.
17: for thou hast cast all my sins behind my back.
18: For the grave cannot praise thee, death cannot celebrate thee: they that go down in the pit cannot hope for truth.

len

With peace and brightest of blessings,

"Seek truth and understanding will follow"

http://www.lensgarden.com.au/