Outboard Help Needed

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Aardee

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Hi,

I've a 2.5hp 4 stroke Yamaha which is refusing to play ball. I serviced it over the winter (oils, impeller, plug), and while it will start and idle it refuses to rev, even in neutral. If I open the throttle the revs increase marginally but it runs very rough. I've stripped the carb and cleaned the jets as best I can without specialist equipment but no difference...Any ideas?

Thanks
 
LadyInBed said:
When you stripped the carb, if you removed the throttle linkage, I would check that.
Click to expand...

Sadly the first thing I checked, throttle is opening just fine. The strange thing is I'd expect the motor to die when extra throttle is applied if were simple fuel starvation.
 
Fuel filter should take a minute to present (the carb bowl would have to empty, though it could be low). Still, check to make sure the bowl is full and that the needle is not stuck.

Sounds like the main jet. I assume it's not just a flat spot (slow to rev, such as a failed accelerator pump would cause). Clean the main jet and passage with spray stuff and a wire as needed. In fact, all carb generally need is cleaning jets. The whole"kit" thing is a waste of time and money 95% of the time.

Another possiblity is bad fuel. Ethanol gas that has separated with do that.
 
thinwater said:
Fuel filter should take a minute to present (the carb bowl would have to empty, though it could be low). Still, check to make sure the bowl is full and that the needle is not stuck.

Sounds like the main jet. I assume it's not just a flat spot (slow to rev, such as a failed accelerator pump would cause). Clean the main jet and passage with spray stuff and a wire as needed. In fact, all carb generally need is cleaning jets. The whole"kit" thing is a waste of time and money 95% of the time.

Another possiblity is bad fuel. Ethanol gas that has separated with do that.
Click to expand...

Thanks, it looks like another jet cleaning session may be called for...
 
Start the engineer and then turn off the fuel valve and try to get it to rev. If, after a while (could take a little time) it starts to increase the revs then it sounds like the float value is not working/ not correctly fitted and the mixture is too rich . Other than that try the old plug.
 
Aardee said:
Hi,

I've a 2.5hp 4 stroke Yamaha which is refusing to play ball. I serviced it over the winter (oils, impeller, plug), and while it will start and idle it refuses to rev, even in neutral. If I open the throttle the revs increase marginally but it runs very rough. I've stripped the carb and cleaned the jets as best I can without specialist equipment but no difference...Any ideas?

Thanks
Click to expand...
Check tank vent , fuel strainer and that you have a good fuel flow to the carb

Did you correctly adjust the mixture . Have you checked the float height ( and drop) ?

Clean the carb again more thoroughly paying particular attention to the main jet. Poke a fine soft copper wire through.
 
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