I have a 2003 20hp Honda outboard, tiller steering and manual start, with very few in the water hours on it. I always run the fuel out of the carb and then drain what's left before I put it away. Dealer says my no start problems are due to the fuel we are all using these days (ethanol).
So today, when it wouldn't start, I decided to clean the carb myself instead of taking it back to the shop for replacement again. The carb didn't look bad inside but I sprayed and cleaned it with carb cleaner anyway. That helped. But it would only run with the choke on. So I opened it up a second time and went through the process again, paying particular attention to the main nozzle, the jet nozzle and the orifice for the SE valve. That was enough to get it to run without the choke on. But it still spit and sputtered and didn't idle well at all, plus I could easily kill it by advancing the throttle too quickly. So I removed the carb a third time (I'm gettin' good at this by now) and again cleaned what now appeared to be a spotless carb. But this time I got no improvement. So I'm stumped at this point by what to do next, other than taking it back to the dealer for another new carb, but that's gettin' expensive. They tell me a new carb is $less$ than they'd charge me for cleaning one though. -shrug-

At the automotive stores, I see the shelves stocked with all sorts of carb and injector cleaners to be added to the fuel tank. Do any of those things actually do any good? I've tried several brands in my old truck with no luck at all so I'm a bit skeptical.

Anyhow, if anyone has any ideas about how to get this thing to run better, I would appreciate it.

Rick

Update:I've completely dismantled the carb three more times, sprayed and blew out every part and orifice I could find, all three times, all for no result.
Talked to the dealer's Factory Authorized mechanic and he tells me I'm wasting my time. Never mind the fact it's still a new carb, I should just buy another new one. It's a common problem that he sees every day. Yes he cleans them for customers that insist on it but it takes several days of soaking and many times even that doesn't work. Even when it's successful, his labor charges are more expensive than just buying a new carb.
He soaks them in his own "concoction" but I couldn't get a straight answer on what his recipe is. Does anyone here have a suggestion for a brew?

Meanwhile, if I keep this thing, I'll be keeping a spare carb onboard along with spare impellers, tools, etc.

Well, turns out the mechanic was right. This has been an exercise in futility and frustration. I should have just pitched my new carb and bought another new one for $160. I'd be way ahead right now in time and $$ money.
The only thing left that I know to try on this carb is replace what is called the "Pilot Screw". I haven't done that before now because, according to the Shop Manual, the procedure involves *breaking off* the old screw, then removing it. Scary part is, there's no mention in the manual about HOW to remove it once it's broken off! I'm thinking drill it and use an easy out???
Does anyone here know?
But as long as I'm now committed to buying a new carb anyway, I guess I might as well go ahead and possibly screw this one up royally.
We shall see what happens next.

There are many ways to remove the pilot screw. If you have already broken it off, find a small dowel or piece of wood about the diameter of a pencil. Use some quick bond epoxy to glue the wood onto the part that is left. Once it is dry, you should just be able to twist the screw out.

Once you clean out the passage, the screw should be turned out 2 1/8 turns.

You should not dip Honda carbs. They have a special coating on them and dipping will take it off. Honda says they should be cleaned in an ultrasonic cleaner.

These carbs have a lot of different passages. Make sure all the passages in the float bowl are clear. Make sure the little plunger in the bowl will shoot fuel out the appropriate hole. The little plunger is the accelerator pump, which you need when increasing throttle.

The long skinny jet going up the inside of the carb takes the fuel up to the idle and transition passages. It has a very small passage up through it. It is almost impossible to be sure that it is clean (I generally just replace it). The idle and transition ports are little pin holes at the top of the rear of the carburator opening. If you take something like brake clean and with the long skinny plastic straw attached to it...with the idle mixture screw just screwed in a couple of turns....take the straw and put it up into the carb where the long skinny jet goes into the top of the carb. When you spray, you should see a nice spray coming out of the idle and transition ports. If you don't see it, then you need to use some very small wire to clean out the holes.

I generally do not use anything stronger than the ultrasonic cleaner (basically water with a solution in it) and brake clean.

These carbs can get quite clogged if there has been water in them. The accelerator pump is especially suceptable to water.

Hope this helps some.

Mike

Thanks Mike. You're the only person I've talked with that has ever even seen this particular carburetor. When I'm looking into the carb, directly above the throttle plate, I see a cluster of 4-5 very **** holes. And nearby, to the side of those holes, but still near the top, there is one hole a bit larger. When I spray into the carb where I've removed the jet nozzle (long skinny one), I get a spray out of all these holes near the throttle plate. Are those the idle and transition passages??
There are also two more of the **** holes, close together, a little further down the side, that I get no spray out of no matter what passage I spray into. I was thinking I might be able to get something out of them if I remove the pilot screw and spray into there. But I don't know. I haven't removed it yet.
The Honda dealer here tells me that pilot screw is the idle mixture screw. So something doesn't make sense because the motor idles fine. The problem is it won't run at high speed. Advancing the throttle will kill it. So I had been thinking the pilot screw and the two **** blocked holes must be the high speed jet. Although granted, those two **** passages don't look large enough to be that. But if it is, that would make more sense than what I've been told.
The accelerator pump and passages are open and working fine.
If you could set me straight on which is the high speed circuit, and how to best clean it out, I think I'd be back in business.
Thanks in advance,
Rick

Thanks Mike. You're the only person I've talked with that has ever even seen this particular carburetor. When I'm looking into the carb, directly above the throttle plate, I see a cluster of 4-5 very **** holes. And nearby, to the side of those holes, but still near the top, there is one hole a bit larger. When I spray into the carb where I've removed the jet nozzle (long skinny one), I get a spray out of all these holes near the throttle plate. Are those the idle and transition passages??
There are also two more of the **** holes, close together, a little further down the side, that I get no spray out of no matter what passage I spray into. I was thinking I might be able to get something out of them if I remove the pilot screw and spray into there. But I don't know. I haven't removed it yet.
The Honda dealer here tells me that pilot screw is the idle mixture screw. So something doesn't make sense because the motor idles fine. The problem is it won't run at high speed. Advancing the throttle will kill it. So I had been thinking the pilot screw and the two **** blocked holes must be the high speed jet. Although granted, those two **** passages don't look large enough to be that. But if it is, that would make more sense than what I've been told.
The accelerator pump and passages are open and working fine.
If you could set me straight on which is the high speed circuit, and how to best clean it out, I think I'd be back in business.
Thanks in advance,
Rick

Those 5 holes are used during transition from idle to higher speeds.

There should be on small on still visable, once you close the butterfly. That is the idle passage. They all do help a little at high speed.

The mechanic is right...the pilot screw and idle mixture are the same thing. Be sure that it is set at the 2 1/8 turns out. You should not have to mess with it very much.

The only other holes in the front are a bit larger and are breathers. Also, there are two air jets in the front of the carb. They are down inside the larger round holes near the top of the carbIt is Be sure that they are clean.

Basically for full throttle, Air comes through those two ports that I just discussed and mixes with the fuel coming through the idle and transition ports as well as out the top of the not so thick tube that the skinney jet goes through after it goes through the main jet.

Mike

A couple of things I forgot.

There is an air vent at the top of the carb the supplies air to the idle mixture.

Also....to check the accelerator pump circuit....if you put the carb bowl on and at least partially fill with solvent (brake clean, etc) then push down on the accelerator pump lever...it should shoot the solvent out the little pipe that sticks out the left side of the inside of the carb at the front.

Mike

Thanks Mike, that's going to be a huge help. You've mentioned a couple of holes inside the carb that I haven't even seen yet so I'll pull the carb off again this weekend and find them.

When I checked the accelerator pump and passage, I did exactly as you described. I got a nice spray down the throat so, it looks pretty good to me.

The pilot screw has a limiter cap on it that restricts its movement to half a turn. This is still a new (zero fishing time) carburetor so I'm assuming it's still set at 2 1/8 turns out. I never did get around to breaking it off. And since it's the idle adjustment, and the motor idles just fine, I'm now thinking I'll just leave it alone.

I guess my next move is to buy yet another can of carb cleaner (or give brake cleaner a try) and find the holes in the front that you mentioned that, for some reason, I haven't found yet.

But there IS something I've been wondering about. Both the Main nozzle and the Jet nozzle inside it, have **** holes in their sides which are located opposite of each other. Do those holes need to face a particular direction? Example, side to side rather than fore and aft? To install them, they just drop in place with no key or pin or anything to make the holes line up in any particular direction. And there's nothing in the Shop Manual that indicates whether or not direction of the holes matter. I've been trying line them up facing side to side when I drop them in place.

I've looked everywhere on the Internet trying to find a schematic of this carb that shows all the passages and jets and breathers etc etc etc. But so far, no luck. Do you know if one even exists somewhere? Sure would make my life easier.

Thanks again,
Rick

It makes no difference how the holes in the nozzle are facing.

Here is a link to a great manual on how to do all the Honda carbs. It has colored pictures showing air flow and fuel flow as well as step by step instructions for cleaning.

http://www.helminc.com/helm/product2.asp?Style=helm

I hope it takes you directly to the page. If not, search for Carburation Manual TM044. If you just put in the TM044, it should come up.

Mike