Honda 9.9 Outboard Stalling at Full Throttle

I just purchased a used sailboat with a Honda 9.9 outboard. The motor is practically new about 40 hours. I took the boat out on the California Delta yesterday and the outboard starts fine but when I engage the throttle forward from neutral and push the throttle all the way forward the motor stalls every time. The motor does not stall until I really push the throttle to almost the forward limit. It does operate if I just nudge it forward a short way but eventually will stall. I started looking at the motor today and could change the fuel filter and air filter to see if that helps. One thing is that I purchased the boat in Denver, Colorado and brought it to California. I wonder if the carb is set for high altitude. Anyone's help would certainly be appreciated.
Thanks

Hi fivepassgeorge! Welcome aboard the forum. What boat do you have? I'm a sailor myownself.

Probably doesn't matter but is it a manual choke or auto? If it's an electric start it's auto. Anyway, there is no air filter to change and I doubt that it is a fuel filter issue.

You may have a point though about the motor being from Denver as there are three different main jets for this carburetor. The link below is the carb parts blow up. If you scroll to the bottom of the page, item 22 (main jet) has three choices. The only way to know which one you have would be to disassemble the carburetor and have a look. I think you are probably headed that way in any case.

http://www.boats.net/parts/search/H...# BABJ-1600001/CARBURETOR (MANUAL)/parts.html

My guess is that you have a stuck accelerator pump piston. Item 14 is the pump assembly with push rod, piston, spring and hold down screw. These carburetors don't like it when there is a problem with the accelerator pump circuit.

Note item 11 in the blow up. If you take off the engine cover and look on the side of the carb, you will see item 11, a rubber bellows type boot seal that is meant to keep dirt out of the carb. The boot is mounted on the accelerator push rod. Locate those parts and see if you can move the push rod down with your finger. Or, operate the throttle while observing the push rod and see if it goes down and then comes back up. If not, that's most likely your problem.

These carbs are VERY sensitive to being put away with fuel still in the fuel bowl and if you don't drain them frequently and try to use fresh, water free gasoline, you will have problems. We always advise to manually drain the bowl with the drain screw as opposed to just running the engine with the fuel line disconnected until it dies. We also recommend that you use a fuel additive such as Sea-Foam to keep the fuel system clean.

It would be good to know what main jet you are running as well because, if one of the leaner jets was installed for high altitude operation, you will want to go back to the larger jet for operating on the Delta.

Sorry to be the bearer of bad news but it isn't too bad as these are GREAT engines with that carburetor being pretty much the only "finicky" thing about them. Many guys repair their own with help here on the forum so, if you go that way, don't be bashful about asking for help.

Thanks for the detailed response. I just bought a used Hunter 240 sailboat. The boat is exceptionally clean however I do need to fix the problem with the outboard. I am going to start working on the motor tomorrow and see what I come up with. The link to the carb is a great help. I may need to change the jet size since I am close to sea level here in CA. I will let you know how I am doing as I work this problem. Great forum.
George

Hi George,

Hunter 240. Trailer sailor? Hunter makes nice stuff. I have old gear myself. A San Juan 23 and a Shock Santana 21. The 21 goes upwind like a banshee and the 23 is a downwind sled.

The boats.net site has all your parts needs at a much reduced price over retail and I would encourage you to purchase a genuine Honda shop manual from Helm Inc. if you're going to be doing your own mechanical work. The Helm manual costs a bit more than a Seloc or Clymer manual but, while those are "one book fits 25 motors', the Helm is focused directly on your equipment. HUGE difference.

Yeah, it's a great forum with lots of knowledgeable help available and thank you for saying so.

I'm sure with a real good cleaning of your carburetor and a new seal kit when it goes back together, you'll be off exploring the Sac River in no time.

Good luck with your repair and don't hesitate to ask questions here.

jimmyd

Well I just had right shoulder surgery so it is going to be awhile before I get to work on the Honda motor. I had hoped that I would be able to get parts locally but no such luck on Honda outboards. I will order my parts/manual through this website and as soon as I can use my arm again I will rebuild the carburetor. Great website.
George

Hi George,
Sorry to hear you're having trouble. Just went through that sort of thing recently myself. I owe my life to advanced western medicine!
Get yourself fixed and we'll be here when you're all healed up! Get well soon.
jimmyd