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Early 2000s bf90 carb head scratcher

S

siscoken

Contributing Member
Just went thru carbs all passages cleaned reinstalled and synched.
Here is confusing part .... engine runs perfect , but the idle mix screw on #4 carb has to be turned practically out to smooth the idle.... it has always been this way.... just removed and went over idle circuit again.... no change.
Once again the engine runs perfect thru all ranges.
 
I've never worked on a 90 so my questions are generic with guidance from the Honda Marine Carburetion Manual. It could take a bit of testing and adjusting to try and clear this condition up.

You probably already know this but #4 (bottom) carb is the "BASE" carb for synching them. Did you set up #4 first then try to match the others with it? It can take a few passes to even them all out.

Does the condition improve if you close the choke a bit?
 
jgmo said:
I've never worked on a 90 so my questions are generic with guidance from the Honda Marine Carburetion Manual. It could take a bit of testing and adjusting to try and clear this condition up.

You probably already know this but #4 (bottom) carb is the "BASE" carb for synching them. Did you set up #4 first then try to match the others with it? It can take a few passes to even them all out.

Does the condition improve if you close the choke a bit?
Click to expand...
Well after cleaning last night and let set till today ... was able to properly set #4 this am... also may have been trying to set idle a little low .... may have been something lingering in one of the body passages..... but apparently cleared now.
 
Well, all I can say is Whew!

That's a relief because I was not looking forward to bugging you to get you to try things and have nothing I suggest work out to get a fix.

People don't take well to open ended suggestions that don't work and I know people get mad at me and often just want me to stop.

So, very glad and grateful that you figured out a solution because correcting a problem like this can sometimes be almost impossible without some luck and more work than anyone ever wants to do.

Congratulations and thanks for updating and explaining what you did.

I hope the rest of your boating summer goes GREAT!
 
jgmo said:
Well, all I can say is Whew!

That's a relief because I was not looking forward to bugging you to get you to try things and have nothing I suggest work out to get a fix.

People don't take well to open ended suggestions that don't work and I know people get mad at me and often just want me to stop.

So, very glad and grateful that you figured out a solution because correcting a problem like this can sometimes be almost impossible without some luck and more work than anyone ever wants to do.

Congratulations and thanks for updating and explaining what you did.

I hope the rest of your boating summer goes GREAT!
Click to expand...
I appreciate the reply and thoughts.... sometimes you need to set a job aside and spend some time thinking and hearing ideas.... I have been troubleshooting carbs a long time and these are some of the simplest which in itself can frustrate.
At times thinking out loud gets a person back on track
 
Agreed.

I used to smoke and cuss.
Working in a big shop, if one of the guys heard me cussing and having a hard time with a job, they would ask "want me to try"?
I learned that if I let them take a turn at it while I walked off and had a smoke, alot of the time they would "get it" and I could move on.
If they didn't get it, about 90% of the time I would after taking the short break.

I quit smoking 40 years ago.
Still cuss a bit though.

But I learned that the old phrase."sleep on it" has much merit when dealing with so many different things in life.
 
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