[Rhodes22-list] Poor throttle response

Michael D. Weisner mweisner at ebsmed.com
Thu Sep 4 18:09:39 EDT 2008


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.
>>>
>>> __________________________________________________
>>> To subscribe/unsubscribe or for help with using the mailing list go to
>>> http://www.rhodes22.org/list
>>> __________________________________________________
>>>
>>>
>>
>> __________________________________________________
>> To subscribe/unsubscribe or for help with using the mailing list go to
>> http://www.rhodes22.org/list
>> __________________________________________________
>>
>>
>
>
> -----
> 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.
>
> __________________________________________________
> To subscribe/unsubscribe or for help with using the mailing list go to 
> http://www.rhodes22.org/list
> __________________________________________________
>
> 



More information about the Rhodes22-list mailing list