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BF20 Hard Start

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BobFino

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I have a 2020 Honda outboard BF20. I am very good about flushing it out after use and running the fuel out before finishing for the day. Recently it is hard starting. It turns over and starts for a few seconds not even a minute. After several tries it will start and stay running, roughly at first. I don't think it is a fuel pump issue because eventually it does start and stay running. Any thoughts would be appreciated.
 
Hi,

Electric start?
Good, fresh gas?
Do you slow troll and/or idle a lot?
Have you ever replaced the spark plugs?
Does yours have the "fuel chamber"? (Black rubber cylinder between the fuel pump and carburetor...mounted on the oil dipstick tube)
Sorry, I have to ask questions before forming an opinion.
 
Last edited:
Hello,
Yes Electric start.
Yes fresh fuel.
Motor is used on a tender so I would say I do not troll or idle a lot.
Have not replaced the spark plugs.
Not sure about the "fuel chamber", would need to go take a look.
Thank you for any help
 
Ok....well...here goes....

The electric start models use an "auto choke" fuel enrichment system that defaults to full start enrichment when the engine is cold. Generally that system only gives trouble when the engine is warm so, for now, we will rule out a cold engine "choke" problem.

It may be a good idea to pull the spark plugs and take a look at them at the very least. I wouldn't think it's time for new plugs on a 2020 model but you never know. You should be prepared to gap them and smear a teardrop sized dab of dielectric (tune-up) grease on the inside of the plug boot lip. The plugs should have light brown color on the ceramic insulator near the electrode and both should look the same. Use the NGK plugs if at all possible....CR5EH-9 and gap to 0.8 to 0.9mm (0.031‐0.035in.)

The fuel chamber (item 2 in the link below) will collect water over time and will cause the symptoms you describe. It needs to be removed and shaken dry every so often. The holder it sits in slides on the engine oil dipstick tube and can be stuck. Use WD-40 to aid in gently sliding it off and back on.

https://www.boats.net/catalog/honda...ta-vin-bamj-1500001-to-bamj-1599999/fuel-pump

You might want to get in the habit of draining the carb bowl into a clear container every so often and checking for water. Running the engine out of fuel is ok but it won't remove water from the bottom of the carb. ALL GAS PUMP FUEL usually contains a small amount of water because of condensation. And, if you leave your remote tank sitting it will slowly build water inside. Draining the carb into a clear jar and checking for water separation is just good preventive practice.

Water is the bane of this little carburetor. Minerals suspended in the water will "plate out" on the internal surfaces and plug up the very small passages and jets. These carbs can be difficult to get clean so you don't want that to happen.

There is a small "bellows" or boot covering the accelerator pump opening on the side of the carb you can easily see. Make sure that bellows is not torn and looks to be properly in place. See item 12 in link below.

https://www.boats.net/catalog/honda...-bamj-1500001-to-bamj-1599999/carburetor-auto

There's plenty of "stuff" being used to combat water in pumped fuel and my current favorite is Chevron Marine Fuel System Treatment with Techron Protection Plus. Some guys use Yamaha Ring Free and some use Sea-Foam. You might want to try something like those to help offset the effects of our continuously deteriorating fuel supply quality.

Good luck.
 
About carburetor draining. There is a drain screw that you can access with a slot tipped screwdriver with the engine hood off. I keep a special screwdriver that is overly long and has a "perfect fit" tip for that screw.

The carb is drained into a plastic hose that leads down to a nipple located just forward of the waterpump tell tale nipple on the stbd engine side cover. I believe that the two nipples are identical.

Little known fact:
The fuel drain hose AND the waterpump tell tale hoses should be replaced every two or three seasons. The tell tale hose especially because, as it hardens, it has a tendency to trap small pieces of debris in the areas where it bends. It should be kept fresh and supple to provide reliable flow.
 
Thank you for all the great information. I do use the Star-Tron fuel additive with each fill up. I will check the plugs and drain the carb to see if any water is present and keep going from there.
 
"The electric start models use an "auto choke" fuel enrichment system that defaults to full start enrichment when the engine is cold. Generally that system only gives trouble when the engine is warm so, for now, we will rule out a cold engine "choke" problem." No experience with this carb in particular, but if it's set up similarly to it's larger siblings using a similar auto choke..... I was thinking that this "enrichening" system COULD be fuel starved. There's a passage in the bottom of the float bowl that feeds it. If there was a blockage in that passage, it could cause the motor to start and act just as described. Further, as it's located right in the bottom of the float bowl, the only way to drain it between uses would be to drain the carb. Running the fuel out always leave a little fuel in the bottom - right where this passage lives..... -Al
 
Thanks again for all the info. I am going to change the plugs, ordered them today. I also drained the float bowl in a cup and it looked clean and no water. If there is blockage in the bottom of the float bowl will it need to be removed to clean out or just draining it should help?
 
BobFino,

Alan is correct...the enrichment system COULD be fuel starved. That's why I stated we would rule it out "for now". The reason being that if it does have a blockage in the enrichment or any OTHER passage then it would be remove, disassemble and clean the carb.

Having said that, I have answered your last question. These carbs are rarely, if ever. successfully "unblocked" by any method other than a proper clean out.

Not something I would want to start out with when trying to diagnose your complaint.

Please don't disregard my advice about removing and completely emptying all liquid from the fuel chamber. The fuel chamber is a unique feature of the BF15D and BF20D and will cause the EXACT symptoms you describe when partially filled with condensate. Taking it off and emptying it should be considered a regular chore associated with these models and, though a pain for sure, a much easier endeavor than a carb clean.

In addition to this I will take this opportunity to implore you NOT to take the chance of RUINING your almost brand new outboard by using ether (starting fluid) to prove or disprove a fuel starvation issue. I always recommend using propane for doing that as it is the closest thing to vaporized gasoline "stoichiometrically" that you can easily use and it is safe for you and your engine if used outdoors. Neither of which can be truthfully said for ether.
 
Ok... definitely agree doing the easy stuff first lol. changed the plugs (the old ones were not gapped properly and looked bad), drained the carb bowl, drained the fuel chamber (yes a bear to remove). What came out of the carb and fuel bowl looked good, I did not see any water. Knowing the motor is so sensitive to water I think I will install a remote fuel/water separator. Ran out of time today, so hopefully I will give it a try over the next few days. Again thank you for all the information. This forum is great!!
 
It's often hard to argue with an add on water separator but I think it's big overkill for this outboard. Regular carb draining and occasionally emptying the fuel chamber is all that's necessary.

While water separators are great for large engines that blow through gobs of fuel, this little 20 sips. Adding a separator just stacks on another regular maintenance item and that's my main reason for not doing it. I've seen too many instances where a guy puts one on and then neglects to service it properly. The result ends up being more problems than he might have had if he hadn't chosen to add one.

Just my opinion and your results may vary ;>)
 
I have remote filters on my larger boat that I maintain every year, I will just add this one to the yearly list. Funny part is I do most of my maintenance on my boat with diesels and for some reason this little out board intimidates me LOL. Waiting for a little better day here in Virginia Beach and I will give it a try. Thanks again.
 
Well I believe I did all that was suggested and I am happy to say it ran great. Not sure which one was the problem or maybe a little of all of them.
Thank you again
 
My guess is that the new, properly gapped plugs probably gets the most credit for your success.

Keeping the carb drained, fresh spark plugs, servicing the waterpump regularly, replacing thermostat, changing the oil on time and adjusting the valves periodically makes these Hondas what I call lifetime outboards. I guess I should add regular LU service and proper shifting technique would probably make it closer to 2 lifetimes. Although, you can pretty much count on the tilt/trim not making it anywhere near that long. But, then, nothing is perfect!

Glad that you GOTTERDUN!
 
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