BF75 Dies at idle and needs 2/3 choke

SeanPenrith

Cadet
Joined
Mar 11, 2008
Messages
6
Hi,

Read a lot on these forums and others about this seemingly frequent issue with these outboards.

I have a 1985 Honda BF75s. The motor has been very reliable over the past summer. I have just put it back into the water and here is the problem:

The motor starts fairly easily with full choke out and throttle at max. This is unusual as it normally starts cold with just the choke out and throttle at idle position. Anyway, once started it revs high, but as I push the choke into 2/3 position, revs pick up and it runs reasonable smoothly. At this point I can move the throttle to the idle position and the motor will run at lower revs, but it is a little unsteady. If I push the choke all the way in or attempt to suddenly accelerate the throttle, the motor dies.

I have new fuel lines, new bulb, new fuel filter, new fuel, new tank, new NGK plugs at the proper gap setting. I cleaned out the carb and check the float which looks clear. Fuel delivery is good.

I read a post someone on here that someone used "easystart fluid" for a similar problem and solved it. What would that do?

Any help or advice would be hugely appreciated since I am reluctant to lug it to a Honda dealer, especially after reading another post that said the dealer could not find the problem either! And, spring is here...dying to get out on the water.

Thanks!

Sean
 

zzzzz

Lieutenant Junior Grade
Joined
Jan 13, 2003
Messages
1,094
Re: BF75 Dies at idle and needs 2/3 choke

inside the carb is a long tube called an emulsion tube and those are prone (especially with your motors age) to developing hairline cracks...remove carb and pull off bowl-you'll see the tube-inspect with magnifying glass...parts diagrams at boats.net :cool:
 

SeanPenrith

Cadet
Joined
Mar 11, 2008
Messages
6
Re: BF75 Dies at idle and needs 2/3 choke

Master Chief ZZZ....excellent, I will try that and let you know how it goes on this forum!

Sean
 

flashback

Captain
Joined
Jun 28, 2002
Messages
3,976
Re: BF75 Dies at idle and needs 2/3 choke

also check the idle passages, I had this problem quite a few years ago and don't remember if there are 1 or 2 very small holes in the throat of the carb near the throttle plate.. I used carb cleaner an compressed air to clear these holes and the engine evened out nicely..hope this may help you..
 

SeanPenrith

Cadet
Joined
Mar 11, 2008
Messages
6
Re: BF75 Dies at idle and needs 2/3 choke

Appreciated Flash. Will check that too. Read elsewhere that I should at the diaphragm...it that at the rear of the motor under the single thumbscrew?

Ciao

Sean
 

SeanPenrith

Cadet
Joined
Mar 11, 2008
Messages
6
Re: BF75 Dies at idle and needs 2/3 choke

Hi ZZZZZZ,

Need a little help if you can. I searched for my model and came up with this link to the carb, but I do not see an emulsion tube. My engine serial # is BF75s-1704860 and does not exactly appear on the search list. Do I have the right one and can you tell where the tube is on the diagram shown in the link?

Appreciated.

Sean
 

eipeldau

Seaman Apprentice
Joined
May 11, 2007
Messages
49
Re: BF75 Dies at idle and needs 2/3 choke

Hello Sean,

The emulsion tube is part number 12 and, indeed, seems not to be available at boats.net. It's also called "main nozzle" and it is part number 16166-881-003. I'm sorry, but I don't know somewhere else for you to look for it. Let's see if the other pals can help.

Good luck!

Henrique
 

zzzzz

Lieutenant Junior Grade
Joined
Jan 13, 2003
Messages
1,094
Re: BF75 Dies at idle and needs 2/3 choke

sorry to say but neither the tube or the complete carb is available from Honda anymore...time to search for used :cool:
 

SeanPenrith

Cadet
Joined
Mar 11, 2008
Messages
6
Re: BF75 Dies at idle and needs 2/3 choke

Hi,

I managed to track down a o-ring replacement kit for my motor from Sport Craft Marina for a little more than $20.00.

With that in hand coupled with carb cleaner, I will tackle this.

Thanks to all for input.

Sean
 
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