BF50A stalls during moderate acceleration

I have a 2003 Honda BF50A which stalls during moderate to fast acceleration. Starts and idles fine, will also go to full rev if advanced slowly and runs great. All round the motor runs good except for the fact that it stalls when advancing the trottle at a fast pace. All was OK until the motor went through a local outboard mechanics shop. At that stage a split fuel line was discovered and replaced, together with a general service. Since then the motor has had acceleration issues, mainly noticeable from 2000rpm and up.

A carby clean was attempted by 2nd mechanic with no success. The motor was then taken to a Honda Marine dealer service mechanic who replaced the low speed pipes, dash pot valves and installed a carby kit. A carby clean was also carried out as well as fuel filter replacement and general service. Problem remained. It was returned to the Honda Dealer who then replaced the plugs, various filters as well as another general service. Problem remained.

The boat is useable providing the throttle is advanced slowly. Havng to do this is not acceptable. Up for any suggestions as each trip to the mechanic has been $$$.

Re: BF50A stalls during moderate acceleration

Is your siphon bulb folding vacuum and supplying enough fuel to the mechanical fuel pump?

Re: BF50A stalls during moderate acceleration

Have you replaced the thermostat, and are you in a cold climate? Let me explain..

I have the 1999 model of that same motor. I'm in a warm climate (S. FL). When you give it full throttle all at once t doesn't stall completely, it just cuts out for a brief moment, as if someone pushed the kill button for 1/2 second, then it takes off like normal. Once mine is hot, it doesn't do this at all, but it does when it is cold. Cold as in it has been sitting for a while, or after extended idle time. Water temps here are in the 70's and air temps in the 70's and 80's here now, so if your climate is colder then that would amplify the problem. 4-strokes need more fuel when they're cold, but these carb'd motors give the same fuel hot or cold so they act like they're lean when they're cold. I'm wondering if your thermostat is stuck open, allowing the motor to cool down too much, causing it to behave as if it is running too lean.

Re: BF50A stalls during moderate acceleration

I just read that your problem started after the local mechanic touched it. Hmm... in that case, it still wouldn't hurt to replace the thermostat, but find out exactly what that guy did to it and then focus on that area. If he got into the carbs, then check anything that might lead to a lean condition. Float levels, gaskets, pinched fuel lines, etc... I have found, time and time again, that no mechanic shop is as thorough as I am when I work. If you can't find a good shop to stand behind their fix, then you might just have to dismantle the carbs yourself and go over them very carefully inside and out.

My Honda 2006 bf 50 a was making oil and stalling at 3/4 throttle . I have ultrasonically cleaned the carbs and reinstalled and balanced them.
The thermostat was stu ck wide open so the motor was running cold. I just have to try the boat on the water now

jam1e said:

My Honda 2006 bf 50 a was making oil and stalling at 3/4 throttle . I have ultrasonically cleaned the carbs and reinstalled and balanced them.
The thermostat was stu ck wide open so the motor was running cold. I just have to try the boat on the water now

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