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Honda BF30 carburetor

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RDarnold

New member
Bought a 1996 Honda BF30A this spring and it was running poorly
could get it to run if you played with the choke but would die as soon as you put it in gear.
Took it to Honda dealer and the cleaned the carburetors twice put them back together but recommended I buy a new motor as they did not think it was worth putting more money into it. I Replaced the neutral switch as I knew it was bad, Then ran a bottle Mercury Quickleen thur it. Motor now runs and shifts fine but when you go to give it throttle it will die. Sometimes if you go slow enough or play with the choke you can get it to go.
Once past start up it runs good and will put the boat on plane with no problems.
I guessing they is different jets.

My question is it the carbs or could there be something else, would be is it worth trying to clean them again or just replace all three carbs?
Shop did say about 140 psi compression on all 3 cylinders.
 
Hi,

First off, this is all just my opinion.....from I don't know how many hundreds of miles away.

I have only worked on one BF 30 A so not much experience with them. I also don't have the service manual for this one.

But I have plenty of knowledge about these "type" Keihin carbs and I study the Honda Marine Carburetion Manual for reference when discussing them.

140 compression isn't spectacular.....but they will run and pull on less....
You might be able to improve that a little by carefully adjusting the valves and doing some decarbonize
treatments.....which is what I suspect you're already started with the Merc Quick Clean.

I suspect though that the improvement you saw after using that stuff does indicate that there is a fuel delivery problem. What is causing that problem is the question.

From what you're describing, I tend to lean toward an acceleration enrichment deficiency. The key component for that is the Dashpot Check Valve....item 41 in the link below:


I also think that there's a very good chance that the carburetors still need some cleaning.

For now though I would keep running that Quick Clean since you seemed to get instant results from doing so.

Again, just my opinion from miles and miles and miles away.
 
Forgot to mention that you can no longer buy the original replacement carbs for this outboard.

While I believe there are some "knock offs" being sold on Amazon, I wouldn't put alot of faith in those working very well....I don't know though.

My advice would be to take good care of the ones you have.

Even when badly contaminated, they can usually be cleaned and reused. I have never needed to toss one yet...knock on wood.
 
jgmo said:
Hi,

First off, this is all just my opinion.....from I don't know how many hundreds of miles away.

I have only worked on one BF 30 A so not much experience with them. I also don't have the service manual for this one.

But I have plenty of knowledge about these "type" Keihin carbs and I study the Honda Marine Carburetion Manual for reference when discussing them.

140 compression isn't spectacular.....but they will run and pull on less....
You might be able to improve that a little by carefully adjusting the valves and doing some decarbonize
treatments.....which is what I suspect you're already started with the Merc Quick Clean.

I suspect though that the improvement you saw after using that stuff does indicate that there is a fuel delivery problem. What is causing that problem is the question.

From what you're describing, I tend to lean toward an acceleration enrichment deficiency. The key component for that is the Dashpot Check Valve....item 41 in the link below:


I also think that there's a very good chance that the carburetors still need some cleaning.

For now though I would keep running that Quick Clean since you seemed to get instant results from doing so.

Again, just my opinion from miles and miles and miles away you
Click to expand...
 
Thank you all for your input. I will order a dashpot sure won’t hurt to give it a try
Seems simple enough to change. Also keep adding the quick kleen. I will go thru the carburetors this winter, probably need to get an ultra sonic cleaner and a set of gages to re-sync the carbs when done.
 
jgmo said:
Forgot to mention that you can no longer buy the original replacement carbs for this outboard.

While I believe there are some "knock offs" being sold on Amazon, I wouldn't put alot of faith in those working very well....I don't know though.

My advice would be to take good care of the ones you have.

Even when badly contaminated, they can usually be cleaned and reused. I have never needed to toss one yet...knock on wood.
Click to expand...
👍
 
Before ordering any parts, there are a couple of tests you should perform.
That check valve receives air pressure from the dashpot diaphragm and directs it to the carburetor fuel bowls to provide a shot of fuel during rapid acceleration. If there is a leak in the diaphragm or other parts of the system, then enrichment won't take place and stalling will occur.
If you plan on doing your own carb work, I can't stress enough how much help the Honda Marine Carburetion Manual would be for you to understand how the system works.
Best $44 you could spend.
It can be ordered here:

Honda Marine | Shop Manuals Publications | Honda Power Products Support Publications

publications.powerequipment.honda.com publications.powerequipment.honda.com

It is listed under "support materials"
 
jgmo said:
Before ordering any parts, there are a couple of tests you should perform.
That check valve receives air pressure from the dashpot diaphragm and directs it to the carburetor fuel bowls to provide a shot of fuel during rapid acceleration. If there is a leak in the diaphragm or other parts of the system, then enrichment won't take place and stalling will occur.
If you plan on doing your own carb work, I can't stress enough how much help the Honda Marine Carburetion Manual would be for you to understand how the system works.
Best $44 you could spend.
It can be ordered here:

Honda Marine | Shop Manuals Publications | Honda Power Products Support Publications

publications.powerequipment.honda.com publications.powerequipment.honda.com

It is listed under "support materials"
Click to expand...
Added to my list
jgmo said:
Before ordering any parts, there are a couple of tests you should perform.
That check valve receives air pressure from the dashpot diaphragm and directs it to the carburetor fuel bowls to provide a shot of fuel during rapid acceleration. If there is a leak in the diaphragm or other parts of the system, then enrichment won't take place and stalling will occur.
If you plan on doing your own carb work, I can't stress enough how much help the Honda Marine Carburetion Manual would be for you to understand how the system works.
Best $44 you could spend.
It can be ordered here:

Honda Marine | Shop Manuals Publications | Honda Power Products Support Publications

publications.powerequipment.honda.com publications.powerequipment.honda.com

It is listed under "support materials"
Click to expand...
 
To my knowledge, the only vacuum readings mentioned in the carb manual are for testing the accel/decel system for leakage and for synchronization gauge calibration. 5-7 inhg in both cases.

If you are referring to expected vacuum readings for idle and cruise for your particular engine, I'm not sure that is listed anywhere. If it were, I believe it would be in the shop manual.

I doubt it though because specific vacuum is related to so many variable factors such as local barometric pressure, humidity, exhaust backpressure, component wear, etc...
 
Beg your pardon....

"normal idle vacuum" for the BF 30 IS listed in the troubleshooting section in the carb manual as 8-9 in.hg.

That sounds a tad low to me but it's also listed the same for the BF 50.
 
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