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Honda BF8D loses power and stalls at full throttle

N

NHfisherman

New member
Hey everyone,

Im having an issue with my 2003 Honda BF8D. I took it out today and within 200 yards of launching the boat I noticed the motor was not getting up to full speed and it felt like it was bogging out. It did stall when I let off on the throttle and then started right back up after. It idles no problem and seems to run fine with 1/2 throttle and lower. I've never had this issue before and it just came out of nowhere. It ran mint a few days ago so I'm pretty confused on what's going on.

The carb was cleaned and put new spark plugs in about 2 months ago and has been used regularly (2-3 times a week). I'm no pro at this stuff so any insight on what I should do would be much appreciated.
 
Try pumping the fuel bulb and see if that makes it work better.
If it does, it might be your fuel pump.
The vent is open on the gas tank right?
 
Probably overheating and going into limp mode.Try disconnecting the temp sensor and try just long enough to see if it runs okay.If it does a full cooling system service and clean would be advisable given the age of the motor
 
So I took the temp sensor off and it did not make a difference. I took the carb apart and cleaned it, checked the fuel pump, spark plugs, and fuel lines. The fuel line assembly going from the tank to the engine was pretty old so I replaced all of that. I did find some pieces of rubber stuck up in the thermostat and cleaned that all out as well so I don't think that was the issue. After putting everything back together the engine was very hard to start and didn't want to idle at first. Eventually after a few minutes it idled fine for about 30 min then I decided to take it down to the water to test it out and had trouble starting it again. Got it going after maybe 10 pulls and about 100 yards down the river at 1/4 throttle it lost power and stalled out. After that it wouldn't stay running even with full choke for more than 3 seconds. Luckily the incoming tide current brought me back to the launch. So whatever I did somehow made things worse. Any other ideas?
 
I think your carburetor cleaning wasn't good enough. It's not that you made things worse it's just that you just altered the symptoms with the less than thorough cleaning. The carb on these isn't easy to clean properly. It needs certain things to be done to get it working again. This requires specific knowledge about how the little booger processes the fuel.

Did you?:

Forward and backward flush the accelerator pump passage in the main body? If so, will the accelerator pump delivery nozzle, located in the brass tube that juts out into the incoming air stream, pass a 6 foot or greater stream of spray cleaner out the back of the carb throat?

Flush the idle air and main air jet passageways?

Inspect the low speed (jet set) tube for minute cracks?

Foward and backward flush the orifices in the top of the carb throat for idle, transition and high speed circuits? And, then you checked that all passed fluid when you finished?

Ensure that the accelerator pump supply "tunnel" in the carb bowl bottom is clear?

Clean both float chamber air vents?

If you answer no or Don't know to most of this, that's not unusual for anyone trying to clean one of these for the first time. These carbs are "fussy" about how they're treated and will be REALLY troublesome if not drained and stored properly.

If most of my questions are baffling to you then you may want to buy and read the HONDA MARINE CARBURETION MANUAL. The manual is really a must have for DIYers and professionals too. It's around $40 and available on Amazon. The manual has lots of pictures and color illustrations of how your carburetor works as well as basic carb theory. It also covers the carburetor models for most of the Honda HP ratings as they are all slightly different. It really IS the EZ WAY to learn how to clean one of these carbs properly. I own one and refer to it constantly.
 
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