Honda O/B Running Rough

Ron20324 · Nov 7, 2011

The fuel pump has a rubber diaphram that can crack and allow fuel and oil to mix. Check it out, but have a new one and change it anyway.

Dan Hill · Nov 7, 2011

I had similar issues with my 9.9 Yamaha when I bought my h240, tracked it down to a faulty stator assembly giving a weak spark. Pull your plugs and check for a nice blue spark when cranking. Good Luck!

tasdevil · Nov 7, 2011

The problem I had with the older Honda on my Oday 22, was finally traced to a worn out cooling impeller : the insufficient volume of coolant automatically triggered performance to drop in self protection.

Ron20324 · Nov 7, 2011

oops- a dup post

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Ron20324 · Nov 7, 2011

saildork said:
If that was happening, wouldn't I have a lot of smoke? I have no smoke, whether the engine is running well or rough.

It has been 19 years, so maybe it's water behind the dia. Either way, check the dia for tears.

timebandit · Nov 10, 2011

Have you ran a compression test on it?

It could just need a valve adjustment after all it is a four stroke.

saildork said:
The outboard on my Catalina 22 is a 1983 Honda 7.5 hp 4-stroke. Until recently, it has performed beautifully since I bought it in 1998. I've never run ethanol in it, service the ports on the carb once or twice a year, as needed, change oil and gear lube when needed, run the carb dry at the end of each sail, etc. In short, I've taken good care of the motor.

Now, it is running rough. No amount of adjustment of the air/fuel mixture seems to help. I recently changed plugs, and that seemed to help for a short time, and then it started running rough again... as if it's not getting fuel or spark to #1 cylinder consistently.

Has anyone had a similar experience? How did you solve it?

Bill Roosa · Nov 10, 2011

Pretty sure it is not the valves needing adjustment. Valves will make it noisy and limit the max power output if they need adjustment. They will not make it run rough.
It sounds like you have already diagnosed the problem. Cyl #1 spark plug change makes it run ok for a while so your fuel system is probably ok and it sounds like an ignition or compression problem. Make sure the plug is the right heat range as the other (numbers all the same on both), check the high tension cables at night with a water bottle that can spray a mist. If you see any blue electric at all replace the wires. Remove the plug and check for nice "fat blue spark" at night also. Inspect both plugs for a uniform brown/tan center insulator.

Technodad · Nov 10, 2011

My feeling on this is that the jets in the carb need cleaning.
My portable genset is a couple of years old and only run a few times, this summer I pulled it out to run it and it would not start at all. Finally I took the carb off and removed the jets and the idle jet was clogged, it is a very small hole so I used one of the wires on my hand wire brush and ran it through it. I put it together and it ran sort of okay, it "hunted", that is it revved then died, revved then died over and over. I took it apart again and really gave that idle jet a good cleaning with the wire, after that it ran like new. First little pull and she runs and idles smooth.
Sorry for the long drawn out tale but this is good info.
I never use fuel stabilizer! maybe I will now?

CaptDon01 · Nov 12, 2011

Rough Running Outboard

My advise,(for what it's worth), when friends have complained about a rough running engine, (2 or 4 stroke), is to first try my "snake oil treatment". It's solved many problems, i.e. rough running, hard starting, dies when idling, etc. I recommend this before you take anything apart, or start adjusting things. First, I always use premium gas, Shell, Chevron, etc. Our little engines use so little gas, I always use the best, and premium gas already has some of the good stuff added. I also add Stabill as directions indicate. I also add about 1/4 can or so of Seafoam, (in the white can, except no substitutes). This is my maintenance routine I follow now. For the initial mix to cure engine running issues, I add a full can of Seafoam to a fresh can of gas, (in a 3 gallon tank, or 2 cans in a 6 gallon tank, won't hurt a thing). Then let the engine run, the best is while in the slip tied up, run it in gear at a fast idle. Let it run all afternoon, won't hurt a thing. The Seafoam cleans out all the little passages in the carb, along with everything else in the carb. It also de-carbonizes the combustion chamber to clean up the carbon from the rings and vavles, (if you have a 4-stroke). When your finished running the engine, let it set in the carb. I NEVER drain my bowl, (I can hear the screaming). The mixture keeps working even when the engine it sitting. I would also run this mixture in my lawn equipment, or snow blower, my Triumph sports cars, and after they would set for the off season, they would start right up, and run like a champ. Snake oil? Possibly so, will other cleaners work?, possibly so, it's just what has proven to work for me for years. Others have followed my "snake oil" method, and have become believers.

Don

keithbennett · Nov 13, 2011

So Don, I have a new (to me) 3.5hp 2 cycle that I have no history with. Whatta ya think about running your mixture for the 2+ hour trip to Steamboat Cove at Havasu? The underlying question is if the motor is running at 50-60% will I benefit the same as what you described?

Keith

caguy · Nov 13, 2011

saildork said:
The outboard on my Catalina 22 is a 1983 Honda 7.5 hp 4-stroke. Until recently, it has performed beautifully since I bought it in 1998. I've never run ethanol in it, service the ports on the carb once or twice a year, as needed, change oil and gear lube when needed, run the carb dry at the end of each sail, etc. In short, I've taken good care of the motor.

Now, it is running rough. No amount of adjustment of the air/fuel mixture seems to help. I recently changed plugs, and that seemed to help for a short time, and then it started running rough again... as if it's not getting fuel or spark to #1 cylinder consistently.

Has anyone had a similar experience? How did you solve it?

I had the Honda BF100 which is the same motor but 10hp. As you said when it runs well it is a perfect motor. They do require a annual carb clean out of the salts that are created by using ethanol. The clean out is a hassle to do yourself in that you will need to buy carb cleaner and have compressed air to blow out the passages. You can also buy and used carb to keep as a back up. They run about $40.
The water in the ethanol reacts with the aluminum bowl. I use air plane fuel now and have not had problems since although it is a different motor.
There are good manuals for your model at the Honda website.
Good luck,
Frank

CaptDon01 · Nov 14, 2011

Keith......Running a rich mixture of Seafoam won't hurt a thing, in fact it's the first thing I did when I bought my Honda, (and my Nissan on the Capri-18 I had). A 2-stroke is a dirty engine anyway, and prone to carbon build-up. Thats where the Seafoam works good to clean out the carbon deposits that accumulate. When I raced model gas engine boats, (basically modified weed-wacker engines), I always used some Seafoam in my fuel. The engines would have zero carbon, and the top of the piston would only have a slight brown stain to the surface. Another thing I do is when we start out on a long trip, (like going to Catalina Island, the wind will just about always be on your nose), so I know we'll be doing 6-7 hours of straight motoring, so I mix a fairly heavy dose of Seafoam in the gas. Just a good time to give the engine a good internal cleaning. When you get to Havasu, ask Capt Howie about his results with my snake-oil treatment on the Tohatsu on his Sanibel. It starts first pull now, idles smooth, even after sitting for months. They call their engine "Don"...

Don't even mention my name, just ask him if he's ever heard about using Seafoam. He's a believer now! Sure looking forward to Havasu again! Unbelievable how this even has grown! And thanks for all the help your giving to the event!

See you there,

Don
"Y-Knot?"

Winkfish · Nov 14, 2011

I will strongly second Capt Ron on Sea Foam. When I first bought my used boat and motor, one of the first things i did was a Sea Foam treatment. I got it off of a boating forum. Basically the same as what Capt Ron said (1 can in 3 gallons fuel), except this one said to run the engine for 10-15 minutes, then let it sit for 10-15 minutes. Apparently that lets the Sea Foam really get at the carb build up. Repeat that cycle numerous times. I just did it until the 3 gallons was used up.

I have since used Sea Foam in a maintenance dose. The can says 1 can to 6-12 gallons - I use 2 or 3 cans for 12 gallons. I love the stuff.

Remember that the Sea Foam counts a "gas" when you figure mixing in the 2-stroke oil.