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Auto Choke on BF20D

C

ChrisHarding

Contributing Member
Hi Guys
My motor is running well with a new carb but although it starts on the first key turn it splutters and dies so I need to restart it and on the 2nd
try it also starts instantly and doesn't stall but the auto choke manages to keep it running and after that it gets smoother and smoother until it's
fully warmed up. Is there any way one can "increase" the mixture richness so I don't need to do the double start sequence. 12 volts is coming in
to the unit but initially there just doesn't seem to be enough rich mixture the first time around. Any ideas ..I don't want to snap off the factory set mixture screw

Chris
 
How confident are you about the quality and volatility of the gas you're feeding it?

Have you tried opening the throttle some while it warms up?

When was the last time that the valve adjustment was checked?

Timing? Compression?

All things I would consider before messing with the new carb.
 
BTW...
...12 volts from the battery or charging system has NOTHING to do with the running of the engine.
That's all for cranking the engine over.

Although, you CAN power a light or radio or other devices from the battery as long as you keep the power consumption low enough for the battery to remain charged up.

Good luck.
 
Hi JGMO
If I open the throttle lever a bit it runs better so maybe I need to just adjust the idle screw a bit? The 12 v I mentioned was the feed to the autochoke and fuel is fresh. On the second attempt to start the motor is fine and warms up perfectly it's purely the fact that it takes a second key turn to restart it and get it running. No big deal really..I can live with it!!
 
These outboards idle best around 900 rpm +/- 50 rpm. While that is high for some people wanting to "slow troll" fishing, it is what it is for this model. Yes, you can adjust THROTTLE STOP SCREW slightly to increase idle speed a little. Maybe that will help with your complaint.
But....
....you do NOT want to raise the idle to the extent that it causes the transmission to go into gear too harshly as that will cause premature wear to the clutch "dogs" and might damage other transmission components.

It might be better to manually increase throttle during warm-up until the idle stabilizes. You'll need to "play around" with it to see what works best.
These carbs are simple devices and the idle speeds can fluctuate a bit due to changing ambient temperature conditions both in the air and the water. So, you need to take that into account while trying to find her "sweet spot" for a reliable idle speed.

The 12v to the bystarter coil after the engine starts is normal and DESIRABLE for proper operation. I'm sure you're already aware of that.

Don't forget to drain your carb before letting the outboard sit unused for an extended time and keep your gasoline fresh and water free. Don't let fuel tanks sit with the vent valve open. Especially during rainy weather.

Good luck.
 
Thanks JGMO
Sadly it stalls too quickly the first time but I haven't tried it yet by lifting the lever slightly and then doing a first start. Yep it idles nicely
after it's warm so I'll leave that where it is. Having bought TWO new carbs already I'm very aware of stale fuel issues so even if I don't go out
I still run the motor every 2nd day or so and make sure my fuel is fresh ..no issues on that side so far now!! I usually forget about the vent so it's "Darn it! forgot to close the vent" and a quick visit to make sure it's closed!!

Chris
 
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