8hp carb question

Hello, this is my first post . I just bought a 2003 8hp honda that is extremly hard to start when cold. I am planning a full carb cleaning, but while searching for parts I found that what I thought was my choke was called a valve set ,starter in the parts listing. The cable from the choke knob leads to a black plastic nut on top of the carb. I am not familiar with this setup. Could someone help explain the proper way to start this engine when cold. I still plan on removing and cleaning the carb. The person I bought this from said it had what he called a bystarter, but my carb (05AD) has this valve set starter.

Hi,
It's got another name too. SE valve or Start Enrichment valve. Bystarter, valve set, SE valve...all the same thing.

You use the choke pull cable pretty much the same way a conventional "butterfly" choke would be used. When the engine is dead nuts cold you would typically pull it out all the way. Once the engine starts and begins to warm up, you start pushing it slowly back in. That's all there is to it.

The problem with them....for the most part...is that cable housing breaks down near where it attaches to the carb. When that happens, it won't allow for getting the mixture to maximum for full cold starting. That sounds like what you have going on.

You can service that portion of the SE with the carb on the engine. Just remove the screw that holds the retainer clip and remove the clip. Disconnect the knob end of the cable from the case and the whole affair should unscrew from the top of the carb body.

The cable (with knob) and the valve set are sold separately. See items 11 and 18 in the parts link below.


https://www.boats.net/catalog/honda...l-range/8hp/bfp8d3-lha-2003/carburetor-manual

I know that they are pricey but I highly recommend that, if yours is bad (cracked) , you replace them both.

Although it may look as if you can get away with just replacing the cable, I have never had any luck trying that.

I hope that this was the info that you needed.

Good luck.

P.S. disregard the screw and clip removal instructions. That's for the electric start bystarter.
Yours should simply unscrew from the body. I get the two mixed up. It's been awhile.

I should have also mentioned that the plastic threads on the valve set are pretty delicate and easily cross threaded and ruined if you get careless or in a hurry. Overtightening the valve set will also ruin the threads. It isn't necessary to get it real tight in the body. Just snugging it down is good enough.

To elaborate on why I say replace the cable and the valve set together is that trying to put a new cable on the old valve set is plain harder than it looks. At least it was for me. I studied it a bit on my first one and thought I could use some heavy duty electrical shrink tubing to mate the two together. After botching it up badly and ruining the new cable housing I decided that I wouldn't try that again even if it was my boss paying for the parts.

Good luck and let us know how it's going.

Thanks jgmo for clearing up my confusion on the bystarter vs the valve set starter that my manual start motor has. I looked at mine and dont see any cracks. but there is some free play in the housing above the threaded nut . Could this be a problem ? I may order these parts and give it a try. Is it pretty self explanatory how to put the two pieces together ( 11 & 18 ) ? When I clean the carb is gasket set # 1 the only new part that is needed to put back together ? Thanks for your help and knowledge.

Silvercrab,

Yes, that play is probably why you're not getting full cold start enrichment.

As far as rebuilding the carb...

If it's running ok other than the cold start it shouldn't need any work.

But if you need/want to go there, be advised that getting these little carbs properly cleaned out isn't as easy as most first timers think. Super small passages and orifices.

And, without specific knowledge about how the little critter mixes the liquid gasoline with the incoming air, several things usually get overlooked.

As far as a parts list goes the #1 gasket set is definitely a must. But there are a couple of other things that you may need to consider.

The first is item #13-jet set.
The low speed jet set has super tiny holes in it and can be very difficult to clean. That little tube is also prone to developing cracks. I got so tired of fussing with them that I would simply replace the dang thang and be done with it. But I was doing many of them and the boss was paying for parts.

Most guys want the accelerator pump (item 22) to be refreshed. Those little pumps don't work all that great and I don't think you'd miss it if the piston was missing. I left one out of a rental motor to see if I got complaints but never did ;>) if you really want the pump to work as designed you would also need to replace the piston AND float chamber as the bore is not repairable. Not really worth the cost in my opinion.

But the bellows (item 21) is VERY important for keeping dirt out. And it's little clamp (item 23) needs to be correctly installed to keep it in place.

Other than that I would consider a new float valve set (item 2) for no other reason than the age of the motor approaching 20 years.

That's about it.

If you do the math on even this fairly short list, you might notice a complete new carb isn't all that much more expensive and that includes the SEvalve set.

People that aren't all that "handy" with tools can choose that option.
You don't strike me as one of those people but, if you plan on owning the outboard for another 20 years, having a spare carb on board is always a cheap form of insurance.

When you have the float chamber off, pay close attention to cleaning out the little tunnel passages at it's bottom. One feeds the accelerator pump and one is the fuel drain. They get packed with "mud" sometimes. Use wire to hog them out if you have to.

Also, with the float chamber off, study how the accelerator pump passage in the bowl meets up with the passage that feeds the accelerator pump nozzle that juts out into the carb throat at the front. With the throttle held/propped wide open, a shot of pressurized carb cleaner into the feed passage should...NO...MUST...result in a stream shooting out the back of carb throat over 6 feet. 8 feet is even better. If it doesn't go 6 feet then the nozzle or tube is partially clogged.

Be advised that the screw heads on the outboard are all Japanese Industrial Screw (JIS)...not Phillips head...and that includes the screws that hold the float chamber to the carb body. They can be a pain to loosen up without boogering up the heads.

Also, a REAL PET PEEVE of mine about these otherwise very loveable, hardy outboards is the way Honda chose to use NO anti-sieze on the air box bolts.

The use of a bronze, captured nut in the plastic housing is almost unforgivable. The "stainless" bolts sieze in the nut and you can easily crack the plastic housing trying to split the air box open to get at the carb mounting bolts. AND...it's almost impossible to spray penetrant into the bottom bolt area.

If you have the time, do your best to get penetrant to those two bronze nuts and let it "creep"" in there as long as possible before attempting to loosen the bolts. Use anti-sieze when going back together.

There is an EXCELLENT book on the subject...HONDA MARINE CARBURETION MANUAL if that interests you. I rebuilt carbs for years before I got mine and it taught me a thing or two.

Any and all questions welcome. There are several great techs watching here that can answer if I can't.

Good luck.

Thanks for detailed explanation. If I buy new carb you would recommend buying the new choke cable also ? How does the cable attach to the valve set. Thanks

Being honest here...it's been so long since I did one, I can't remember all the details about inserting the cable. I think it simply slides into the valve's conduit but it's probably a tight fit and has to be engaged "just so" for the valve to work properly. I cleaned many many many of those carbs but only had to replace a handful of the SE valve sets. They're pretty reliable until they're not.

If you can get yours off the carb ok you should be able to see how it goes together. Who knows? If you don't see any material deterioration, the two may have just come unhooked from each other???

If your cable seems ok you might get away with reusing it. I just remember saying that I was never going to try and reuse those parts again when it went wrong. And for $20 and a looong wait for shipping, it's not worth it to skimp. But that's just me.

I worked on rentals and the customers would always try to "fix" them before I got to them. I would try that too if it wouldn't start and I was stuck out on a lake all by my lonesome.

Sorry I can't be more specific but getting old and time hasn't helped the memory as much as I would have hoped.

As an aside (sort of)....the reason I emphasized getting the accelerator pump spray nozzle clean enough to deliver a 6 foot stream while at the same time saying how ineffective the system was is this:
If that nozzle is plugged, or even partially plugged, the outboard will be hard starting and will not run very well at all. I don't really know why that is. I believe it's because that the circuit acts somewhat like a vent of some sort. It doesn't matter if the pump itself works properly or not. You would want that little nozzle clean for your outboard to run correctly. Just clearing that up.

Keep us updated on progress please! We all love to read about the trials and successes of DIYers that keep these GREAT Honda outboards up and running.

Update. I decided to unscrew the se valve and look at it. I pulled the choke knob in and out a few times to see if it was working ( it was ) and I squirted some carb cleaner in the opening and drained the carb, closed drain, pumped bulb, pulled choke knob, held my breath and pulled the rope, IT STARTED FIRST PULL. I will try starting again tomorrow cold and see if it was a fluke. If it works again I will hold off further action, but it probably needs a good cleaning. Thanks for all helpfull information. I will update if it fails again.

Update. I decided to unscrew the se valve and look at it. I pulled the choke knob in and out a few times to see if it was working ( it was ) and I squirted some carb cleaner in the opening and drained the carb, closed drain, screwed se valve back in , pumped bulb, pulled choke knob, held my breath and pulled the rope, IT STARTED FIRST PULL. I will try starting again tomorrow cold and see if it was a fluke. If it works again I will hold off further action, but it probably needs a good cleaning. Thanks for all helpfull information. I will update if it fails again.

Well, that is encouraging.

Maybe it just had some gunk stacked up in the wrong place.

If it continues to start, you might want to try running some stuff in the fuel like like Sea Foam or the Yamaha product. Ring Free I think it's called.

I've been using Chevron Techron Marine Fuel System Treatment in ALL my gas powered engines.

I started using it after someone else on the forum suggested it. It claims to be a 2 year fuel stabilizer as well as a cleaning agent and is MUCH more economical than anything else out there afaik.

2 oz.. treats 10 gallons of gas and I buy it by the case on Amazon.

It's meant to be added at every refuel and that's what I do but to each his own.

Using good quality, fresh fuel and maybe an additive is going to be your best defense against problems with that little carb.

They built in a drain screw with a hose to the outside of the case and you should drain the float chamber at regular intervals while you're using the outboard and anytime it's not going to be used for more than a month or so.

update #2. My success was short lived when earlier I removed the valve set and squirted carb cleaner in the hole and it started. The next day it was once again very hard to start. So I followed jgmos expert detailed cleaning procedure and took carb apart and cleaned it. It was partly plugged in the orifice that the valve set attaches to, I cleaned every orifice and passage I could find. So far after two fishing trips it runs and starts perfect. Thanks again jgmo for your help

Alright!
Success!
That makes me feel good.
Thanks for the update and for hanging in there and gettin' 'er goin' again!

Update #2. Well I was proud of myself for awhile. Motor is once again hard to start. It just is not getting fuel on cold startup, once it finally does start it runs perfect all day long. When cold it will start if I pull breather hose off airbox and spray starting fluid in there. Either something has plugged inside carb or the valve set auto choke is faulty. When I cleaned carb a month ago I also changed fuel filter and have used new gas since. It started cold and ran perfect for weeks. Heres a dumb question. If I get a new carb does it come with new accelerator pump inside. The diagram of my carb shows part #22 accelerator pump, but you cant purchase it seperately.

Most "first timers" don't get these carbs completely clean. They are simply tough little boogers to get all the gunk out. That's why I recommend the carb manual that walks you through it with pictures OR a new carb.

I've had guys here clean them 7-8 or more times and finally get positive results.

My guess is that you either didn't get the passages in the bottom of the float chamber clear or you didn't get the jet-set completely clean. OR...the jet set tube is cracked and you didn't see it.
Those are the areas that cause the most hard/no starts

I didn't re-read all of the above but did you have a 6 to 8 foot stream of cleaner spray come out of the accelerator pump orifice? That's very important.

Did you backflush each drilling at the back of the carb throat?

Did you remove the idle mixture screw and flush the idle passage?

Did you flush the main air and slow air passages from the front mount flange?

See? Those are just SOME of the procedures that need to be done.

You simply can't be expected to know all of this first time out.

As far as the accelerator pump goes, yes it will come with a new carb. But you can also buy the parts for the pump separately. See item 22 and 21 in the link below.

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/8hp/bf8d3-lha-2003/carburetor-manual

While the pump push rod extends up through the main body it is actually a part of the float chamber. If the pump piston bore is scored (most are) the bore isn't serviceable and a new float chamber is the only solution for a "total" repair along with a new piston and spring.

While the accelerator pump CIRCUIT in the main body is very important to keep clean for reliable starting and running....
....I'm completely confident that the pump itself is NOT causing your start up issue. I have actually run this exact same outboard WITHOUT the piston and spring in the bore. Also, about 100% of the pistons will eventually sieze in the bore and the outboard will still start and run well.

Bottom line? The accelerator pumps on these are almost worthless but the CIRCUIT needs to be clean for the engine to run properly. I admit that I can't fully explain why but I do have plenty of experience with this being the case.

I do wonder if your "choke cable" is working properly. If it isn't, you will have the same problem even with a new carb.

I am not sure that carb manual is still available. When I unscrew the valve set from top of carb and pull the choke knob the little valve set is pulled up into plastic nut. I assume thats what it is supposed to do. I might give one more clean job before I purchase new carb

The carb manual is still available but ONLY from one source AFIK. I have attached the link to Honda Marine Publications. Scroll down about 3/4 of the way and it is there. $43.95 + shipping and tax.

https://publications.powerequipment.honda.com/marine

Thank you for info.

Another question for jgmo. I want to get this running good then sell it, I got a good deal on a suzuki 9.9 electric start EFI. No more carbs for me.I have had a 20hp EFI suzuki for seven years now, you can let it sit for 6 months and it starts instantly. Never a bit of trouble. Sorry for the rant, back to the question. My honda will start first pull cold every day, but if I skip a day and let it sit for two days not so good. Same method, pump ball, pull out to fake choke knob and pull the rope.Whats up with that. I have not taken the carb off again to clean. If I put a new carb on is it plug and play or are there adustments needed

That IS a weird symptom but still sounds like the cold enrichment issue you've been chasing. Have you tried artificially enriching it when the problem is present? I like to use propane to "prove out" an issue like this but it's hard for me to convince anyone to spend the $20 or so and top the "learning curve" to try it.

You can spend $10 and buy a can of carb spray and a section of hobby shop fuel hose to snake up into the intake box....but it's INFINITELY more DANGEROUS because of the liquid, highly volatile medium you'd be messing with.

To answer your question...
Yes, the new carb is SUPPOSED to be set up, ready to go. But that's only if the problem IS the carb AND the engine is fairly "fresh".

And note that the new carb doesn't come with a new "choke" cable which I have already expressed my opinion about.

Good luck with your new Suzuki.

If I let it sit a few days and it doesnt want to start I can pull breather tube from airbox and squirt starting fluid in and it will start first pull.

Hello again jgmo, hopefully this will be the last time I have to seek your help. I finally got around to taking the carb off and will attempt to clean it again. I noticed some crud in the bottom of float bowl, I have cleaned everything up, but am not sure about something you said that is very important.You said with the throttle wide open to shoot carb cleaner into the feed passage and it should result in a stream out the back of the carb throat about 6 feet. Is it possible for you to show a picture of exactly where you are meaning. Thanks Phil

You have the carb apart right?
If so, look into the FRONT of the air tube or "Venturi" and you will see a slender brass tube. At the very end of that tube is a very small nozzle that faces toward the outlet end of the venturi.

To see the nozzle clearly you will need to use a small screwdriver to prop open the throttle linkage so that the throttle plate is horizontal. Then, you can look in to the carb from the rear and see that nozzle..

Take a can of carb spray with the plastic straw attached and very carefully put the end of the straw over the nozzle and spray the heck out of it. Carb spray should dribble out of the accelerator pump passage that feeds that nozzle. You don't need a photo to follow the trajectory of the brass tube back into the carb body and find the passage. I'm in no position to do graphics for this site at the moment.

Once you locate the passage, and with the throttle linkage still propped fully open, spray the cleaner into the passage opening and a 6 foot MINIMUM stream should come out the nozzle and exit the back of the carb throat.

If it doesn't, repeat the process of spraying the nozzle end with cleaner then back in the passage. Back and forth, back and forth.

I have never had one that I couldn't clear that way.

If you found crud in the bottom of the float chamber though, did you clean out ALL the passages in the bowl with wire? They get pretty packed in sometimes.

Good luck.