[Rhodes22-list] Poor throttle response

R Orkin roryorkin at verizon.net
Thu Sep 4 19:04:16 EDT 2008


I am not smelling anything that suggests rich on fuel..
The automatic choke is suspect for sure..
I do not know if there is a separate mixture adjustment for idle .
if at idle and you suddenly crank it then it stalls right away.. does sound
more like fuel starved than too rich. It is a yamaha 9.9 .. I am going to
look at a parts diagram to see if it does have an accelerator pump.
I want to work around to the carb itself as a last resort. I am not going to
tackle it and it is hard to get anyone around here to look at it in less
than 2 weeks.. I can run like this till the end of the season but would like
to try to fix it in place. 

R22RumRunner wrote:
> 
> Or, it could be starved for fuel. How does the exhaust smell? Rich or 
> normal?
>  
> Rummy
>  
>  
> In a message dated 9/4/2008 6:10:15 P.M. Eastern Daylight Time,  
> mweisner at ebsmed.com writes:
> 
> Rory,
> 
> I do not recall what specific engine we are discussing so  all comments
> are 
> of a general nature (not all outboards have an  accelerator pump.)
> 
> It sure does sound like too rich a mixture.   Look for the choke.  Follow
> the 
> actuator mechanism if you have to -  the choke is somewhere at the air
> intake 
> of the carb.  It usually  looks like a disc in a tube that rotates to
> close 
> off the air intake  during cold starting.  When fully open you should be 
> looking at the  thin edge of the disc.  When fully closed, you should be 
> looking at  the "top" (flat portion) of the disc, as it blocks most of the 
> air  passage.  Partial choke setting opens the choke mechanism to some  
> degree.
> 
> Air filters in many outboards are actually in the  housing.  If your
> engine 
> runs fine until you replace the housing,  look for a very clogged air
> filter. 
> If the air filter was the problem, the  engine probably would not run at
> high 
> speed at all.
> 
> The problem may  be that the idle mixture is set incorrectly or that the
> main 
> jet, which  sets the high speed mixture in many outboards, was damaged
> when  
> cleaned.  This can occur if the mechanic did not set the main jet 
> actuator 
> correctly.
> 
> It would be nice to know what was disturbed to  limit the possibilities. 
> I 
> would check the float and needle valve  anyway, just to be sure.  It does
> not 
> sound like a carb cleaner  problem at this point.
> 
> Mike
> s/v Shanghai'd Summer  ('81)
> Nissequogue River, NY
> 
> 
> From: "R Orkin"  <roryorkin at verizon.net>Sent: Thursday, September 04, 2008 
> 5:54  PM
>>
>> The carb was cleaned recently but not by me so I dont know  if the fuel 
>> float
>> is the problem..
>> Where do I look  for occluded choke passages and how do I clean them.. ?
>> I was not sure  if there was an accelerator pump on this model. Was that
>> a
>> general  observation or specific to the outboard.
>> I don't know where an air  filter is unless it is right up against the
>> carb
>> behind the air  intake
>> Mixture is the most likely culprit but I need to check out some  of the
>> other things so I don't try to compensate for another problem  with the
>> mixture.
>> There is a real lag between motor trying to  pick up the fuel on sudden
>> acceleration..
>> which is why I think  it is not the carburator float. A quick turn of the
>> handle leads to  immediate stall.
>> It is not burning off the fuel in the bowl then  stalling. The valve must 
>> be
>> working somewhat or it would not  refill at high rpm. If it is in the
>> carb 
>> I
>> am thinking fuel  residue.. Will a fuel line aditive actually clean 
>> anything
>>  out ??
>>
>>
>> R22MikeW wrote:
>>>
>>>  Rory,
>>>
>>> Since you can get to full throttle (slowly) this  rules out problems
>>> related
>>> to supply of air (air  filter is OK) and fuel (fuel filter, tank vent, 
>>> fuel
>>>  pump, etc. are OK) and also ignition.  If it stalls on sudden
>>>  acceleration,
>>> the problem is either due to too rich a fuel mixture  (check for
>>> occluded
>>> choke passages, improper mixture adjustment,  improper accelerator pump
>>> action, etc.) or more likely, improper  fuel bowl float setting (sudden
>>> acceleration will burn the fuel  before it is replaced by the pump.)
>>>
>>> Have you cleaned  the carb out recently?  If so, did you bend the float
>>>  adjustment?  The purpose of the fuel bowl is to maintain a fuel 
>>> reservoir
>>> for rapid changes in fuel consumption so that the engine  is not starved
>>> for
>>> fuel.  The float is adjusted  so that it maintains a particular level in
>>> the
>>>  bowl.  It opens and closes a small needle valve in the fuel inlet 
>>> line,
>>> regulating the flow into the bowl.  Too much and the  engine "floods"
>>> with
>>> fuel; too little and the engine runs out of  fuel (starves) when rapidly
>>> accelerating.
>>>
>>>  Small engine (carbureted) 101 ...
>>>
>>> Mike
>>> s/v  Shanghai'd Summer ('81)
>>> Nissequogue River,  NY
>>>
>>>
>>> From: "R Orkin"  <roryorkin at verizon.net>Sent: Thursday, September 04,
>>> 2008
>>>  4:42 PM
>>>>
>>>> My 9.9 Yamaha has had a variety of  starting problems. All seem to be 
>>>> fuel
>>>>  related. I seem to have it cleaned out to the point it will start  but
>>>> still
>>>> have poor response from the  throttle. Sudden acceleration will stall 
>>>> it..
>>>>  slow acceleration is ok and I can get full throttle.. Does this seem 
>>>> to
>>>> be
>>>> a
>>>> mixture, fuel pump or  other problem to anyone? perhaps  automatic
>>>> choke
>>>> issue  ??
>>>>
>>>> -----
>>>> Rory  Orkin
>>>> Tilghman, Md
>>>> 2000 Recycled  Rhodes  22
>>>> Duet ll
>>>> -- 
>>>> View this  message in context:
>>>>  http://www.nabble.com/Poor-throttle-response-tp19319533p19319533.html
>>>>  Sent from the Rhodes 22 mailing list archive at  Nabble.com.
>>>>
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>>>
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>>>
>>
>>
>>  -----
>> Rory Orkin
>> Tilghman, Md
>> 2000 Recycled   Rhodes 22
>> Duet ll
>> -- 
>> View this message in context:  
>>  http://www.nabble.com/Poor-throttle-response-tp19319533p19320793.html
>>  Sent from the Rhodes 22 mailing list archive at Nabble.com.
>>
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>>  http://www.rhodes22.org/list
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>>  
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-----
Rory Orkin
Tilghman, Md
2000 Recycled  Rhodes 22
Duet ll
-- 
View this message in context: http://www.nabble.com/Poor-throttle-response-tp19319533p19321799.html
Sent from the Rhodes 22 mailing list archive at Nabble.com.



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