Honda bf90 leaking fuel from carb vent

Hello,
I believe my bf90 is a 1999. I just put the boat in the water for the first time this season today. I noticed a fuel leak and after scouring this board I learned that it is coming from the fuel vent on one of the carbs (leaking from the silver disk about 3/4"). Leaking from the bottom carb on the port side. I have not worked on an outboard before, but the fix seems easy enough for me to give it a shot. I read about draining the carb, and tapping with a screwdriver. I have not gone back and looked at the motor since finding this forum, so my question(s) are. exactly how do you drain the (1) problem carb? Is there a drain screw on each carb ? Does the tapping method have a high level of success? Should I be adding Seafoam to my fuel? And most important...can the engine be safely operated to the boat ramp ? Or should it not be run at all with this fuel leak? Thanks very much for helping out a newbie.

Hi bob1008,
Your photo shows the drain screw for the carb in question and also the one above it. It is the slotted head there on the bottom corner of the float chamber. Yes, each one has it's own drain. Refer to the parts break down for the carburetor in the link below.

http://www.boats.net/parts/search/Honda/Outboard Engine/1999/BF90AX LHTA /CARBURETOR/parts.html

The "tapping method" can be quite effective for shaking loose a stuck float but not always. It is certainly worth a try though.

Yes, by all means you should use Sea Foam in your gas. It is tried and TRUE. But, like the tapping technique, it has it's limitations. It is no substitute for a tear down and clean out for a troublesome carburetor. If the tapping stops the flooding and you can add the Sea Foam and experience no more problems, then great. But if it keeps happening, you're looking at a service on ALL the carbs since it will probably start to happen with the others eventually anyway.

It is NEVER a good idea to take chances with a gas leak on the water. You might get away with it but a gas fire on a boat can be life threatening for more than one reason. Think about it. If the engine were to catch fire, you would have to shut it down and abandon the helm to go put it out. Now you're out of control, adrift AND on fire! If your waters have any traffic at all, the fire would only be a small portion of your emergency and the danger you would be exposed to.

I recommend setting up a tow to get it to the ramp or, depending on what's available and the distance involved, you could use a trolling motor or borrow a small kicker to temporarily power to the trailer.

I hope this helps you in some small way. Good luck and keep us updated.

Well I went down to the boat today and followed the very helpful directions here.
a) Drained the carb by loosening the screw. There is a permanent drain tube connected to the nipple of the lowest carb, so it was easy to drain.
b) Tapped as directed quite a few times in several places.
c) Closed drain screw and primed motor. I noticed that the fuel 1st comes out of another drain tube before it come from the vent.
I've attached a picture below with the red arrows showing the drain tube that leaks fuel before the vent leaks.
d) Drained carb again. Closed screw
e) Got as much Sea Foam down the tube as possible and left it for tonight.
Any input or suggestions would be greatly appreciated. Thanks. Bob

It is still a stuck float. It is leaking out the front of the carburetor, then going coming out the breather hose for the intake muffler.

Hopefully, the sea foam will break it loose.

Mike

Thanks hondadude. Just needed to get some reassurance that I'm still on the right track. I will attack it again tomorrow.

One thing more that you might try is removing the drain screw completely and spray carb cleaner or WD-40 directly into the float chamber. This has worked for me many times. I like the WD because it has SOME lube quality and it is pretty cheap so you can blast a whole can at the problem and not be out lots O monies. Use the straw that come with the can and stick it in that hole and blast until it comes out. WD is FLAMMABLE but nowhere near as dangerous as gas or carb cleaner so having it leak won't be a big danger. It has a VERY high flashpoint compared to carb cleaner.

So, it goes something like this: Rinse, tap, repeat. Rinse, tap, repeat. JUST DON"T LOSE THAT SCREW!!

The screw is non magnetic and could be hard to retrieve. Fashion a "catch" basket for it out of a sheet of paper and slide/fit it under the carb to catch that screw if it gets away from you.

Good luck.

jgmo said:

One thing more that you might try is removing the drain screw completely and spray carb cleaner or WD-40 directly into the float chamber. This has worked for me many times. I like the WD because it has SOME lube quality and it is pretty cheap so you can blast a whole can at the problem and not be out lots O monies. Use the straw that come with the can and stick it in that hole and blast until it comes out. WD is FLAMMABLE but nowhere near as dangerous as gas or carb cleaner so having it leak won't be a big danger. It has a VERY high flashpoint compared to carb cleaner.

So, it goes something like this: Rinse, tap, repeat. Rinse, tap, repeat. JUST DON"T LOSE THAT SCREW!!

The screw is non magnetic and could be hard to retrieve. Fashion a "catch" basket for it out of a sheet of paper and slide/fit it under the carb to catch that screw if it gets away from you.
Good luck.

Click to expand...

I was thinking of trying something like that with Fluid Film lubricant. The problem is I'm dealing with the bottom carb and that screw is very low. I can barely get to it with a screwdriver. There is no way to get my fingers anywhere near that screw. But now that you have brought up that idea I'm thinking about trying to shoot the Fluid Film in thru the hose to get into the carb. I'm not sure how much of the Sea Foam made it down the tube and into the carb. That lower carb sits really low in the bottom cover. Very difficult to get to.

Yeah, I hear ya. Better to punt than to make things worse by having a "permanent" leak due to lost screw. But, if you can open the drain and get the "juice" up through the hose, that might work too. Good idea.
Good luck.

Tried everything to fix this float . Nothing seems to work so far. But I'm learning a lot . I was able to spray enough WD40 into the drain hose until it started to come out of the vent disk. I tapped repeatedly many times, and flushed many times and no luck. Now that I know that spraying into the hose actually works, I'm going to pick up a spray can of Sea Foam or CRC Carb Cleaner and try spraying that inside. I stopped by my Honda dealer today and the mechanic there said I would be much better to spray the carb cleaner into the FUEL tube that feeds that carb, instead of into the drain tube. Not sure if I can get access or even that fuel tube easily, but I'm going to go down and look for it today. He said "when I see it, it will make sense".

I would not, necessarily, argue against spraying in through the inlet. Either way is ok and both ways is even better.

But, it is the float that is stuck, holding the inlet valve open, not the valve itself. Think of it this way; if you could get a substance in there that is more "buoyant" than gasoline, it might put enough pressure from underneath the float to sort of push it up and "break" it free.

Ironically, water would probably be more effective than anything discussed so far. The one thing we all try to keep OUT of our carburetors! But, if you're going to have to tear 'em down and clean 'em anyway it might be worth a shot.

You can flush it out with WD-40 afterward since one of that products most desirable attributes is that it does, indeed, displace water.

Simply pressurizing the chamber from either "entrance", no matter what you use, probably won't do it, given the laws (Pascal's) of hydraulics, but it is certainly worth a try too.

And keep tap, tap, tapping all the while. It just may pay off yet.

Just reading what I just wrote and WD-40 is STILL the best thing to put in there that I can think of. If it "displaces" water....?

Tap, tap, tap. ~)>

Beware of carb cleaner in your fuel line. It could breakdown the rubber and you might wind up with more of a mess than you now have.

Mike

update:

Well.. I could not get anywhere with the flushing and tapping, so I threw in the towel and hired the boatyard where I keep the boat to look at it. They are not a Honda Dealer, but they do a lot of outboard work. I got a call from the mechanic that they "ordered the kit and the carb leaking issue is all set". I did not get a chance to get down there and find out in detail what the issue was, or what they did. He asked me what my normal cruiseing rpm was because he was surprised that the boat did not have more power. I was surprised that he said that because that boat flies.

Anyway, I went down to the boat today (sunday) to take a nice ride on my boat. It will not accelerate at all and will not even get on plane. The engine appears to run smooth and idle well, but it won't accelerate. At wide open the rpm reads 4200 and the boat is barely plowing thru the water. Nowhere near on plane. Previously the boat always planed out at about 2500 - 2800 rpm.

I did notice also that the throttle does not go anywhere near as far forward as it did previously. I used to be able to push the throttle almost all the way till it hit the console. Now it stops 3" - 4" short.

I also noticed that the brass pin only goes about halfway up the black plastic bracket in the pics attached. (Sorry, I don't know the correct names for these parts.)

So my dilemma is, do I call the same yard tomorrow and tell them about the problem, or pull the boat out of the water and bring it about 30 miles to the closest Honda Dealer ? The mechanic at the yard where the boat is now seems to be a fairly esperienced guy and I asked around the marina and got several good reccomendations on him.

I would go back to the guy that did the carburetors. If he took the entire intake manifold off, as he should have, and removed the carburetors, he would have disconnected the cables that you see attached to the throttle lever.

Most likely, he did not adjust them correctly for proper movement to full throttle. If he took the other ends that are on the other side of the motor, those may be out of adjustment also. The brass piece/roller should go practically to the top of the throttle bracket.

If he is as reputable as the recommendations say, then he will fix the problem. It is not hard to get back into adjustment. As someone who does not usually work on Hondas, this is a simple mistake to make. He just has to go back to where he disconnected the cables and readjust for full throttle.

Mike

Hondadude will have the definitive answer for you on the throttle pic. I'm pretty sure the pin should travel all the way up the ramp so it is clear to me that the mechanic missed the throttle linkage/cable setup pretty spectacularly. This would indicate that he has never done one before (like me) and doesn't have the shop manual (like me) for your outboard OR, has the shop manual and didn't read (like me, sometimes) the throttle linkage procedure.

It is a little disturbing that he got to this point and didn't/couldn't figure out (unlike me I would hope) that he had left you with a little problem.

But, I heard tell that these throttle cable setups can be a bit tricky to adjust properly and he may have encountered a situation where he thought he might break something so he stopped short. I don't know. I've never done one either.

It's just obvious he needs to go back and make it right for you or give you your money back. From what you've said, that others have recommended him, then I would let him correct his error since he sounds like he's on the up and up if not totally prepared for all makes and models. Have a talk with him about it at least.

Sorry you're having such difficulty.