Dinghy outboard having some issues

Hey TF,

Another question to run by the collective genius of this forum. I have an older dinghy with a 9hp 4 stroke motor. Both came with the boat when I bought it last year. The dinghy had been sitting for a while, so the girlfriend and I took it out for a spin late one night to get the fluids moving around. It started up and cruised along just fine at first, but after cruising around for a bit we managed to stall out going over a medium sized swell just a little bit too fast. We got it started back up again, but ever since then the outboard won't go past idle. Now when I start it up it will hit a rough idle, but if I give it any gas at all the whole thing just dies on me.

Any thoughts on what might be causing this? The fuel line looks like its letting gas through alright (although I'm not 100% sure on this) and I can't see anything else amiss based on a visual inspection. Seems like its probably a fuel or air delivery issue, but not sure how to narrow it down beyond that. The only fuel filter it has is a little screen fitting attached to the bottom of the intake tube in the gas tank, and it looks clean. Any thoughts or diagnostic tips greatly appreciated.

Thanks!

Could be as simple as bad fuel and a gummed up carburetor. Once you get the problems sorted I suggest you run the thing on non-ethanol fuel. Doing this solved all our small gas engine problems, from chain saws and lawn mowers to 2 and 4 stroke outboards from 4 to 90 hp.

Thanks Marin. You're probably right about the gummed up carb. Sounds like it's going to need a trip to the mechanic... something I was hoping to avoid. Good 'lesson learned' though, shouldn't have let the gas sit so long.

drain and try new gas. Worth a try

If you can get at it remove the drain plug for the carb bowl and flush it out real good with carburetor cleaner spray.

Give sea foam a try prior to paying a mechanic.

Here's a theory, when you went over the swell too fast, you stirred up a slug of crud from the tank and the filter clogged. Sounds like we all suspect a fuel problem.

Simply draining the carburetor as Capt. Bill suggests and then feeding the engine fresh fuel can work wonders.

P.S. always carry oars or a paddle.

Brooksie said:

drain and try new gas. Worth a try

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Lots of good advice here. Don't forget to change the fuel filter, too. If it's an old gas can, I'd get a new one.

Try googling the particular outboard motor. I found a u-tube for my Nissan on how to clean the carburetor. It was dead on. The same issue you are having, and it is also a 4 stroke, and it was a little booger in one of the jets for the carb. The first time I did it I still had the problem, the video said "if it still does it, do it again" and I did, and it really did fix it. It's amazing what you can find in fix it videos on u-tube.

Good practical answers.I got sidetracked by" the girlfriend and I took it out for a spin late one night to get the fluids moving". I need to get out more. I`d have thought a gummed up carby was more likely in a 2 stroke than a 4 stroke.

I`d have thought a gummed up carby was more likely in a 2 stroke than a 4 stroke.
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A carb. is a carb. and the jets and ports can get plugged resulting in no or rough running.

On small engines like this the the ports and jets are tiny so dirt that a car carb. could pass will plug the outboard.

You should have some kind of a filter leading to the o.b. or any tank dirt will plug the jets. If you do, change it. Also take a look at the fuel lines and the hose clamps. If they have poor connections then air can be sucked in stopping the fuel flow to the engine. I once had a metal, in line, filter rust a pinhole. Wouldn't idle worth a darn but once running fast the small amount of air was overcome. Once home I changed the filter and no more trouble.

Lots of good tips, thank you all. We live aboard and I store the outboard up in the flybridge (had to take the davits off to pass the measurement when we got our slip) so its tough to get at the engine or do any real work on it from here. Im hoping to nail down some garage space soon though so will try these things that you guys suggest. It would be nice not to have to pay a mechanic.

Thanks again.

We bought a dingy and a used Yamaha 4 hp outboard last spring when we bought the big boat. I've been around boats since a little kid, but even so, I had never really worked on an outboard. The outboard ran fine for a while then quit, just could not get it started again. I was afraid carb work was way out of my skill range - they look outrageously complex - but it really wasn't too bad. I took mine apart step by step. I followed a lot of the advice you have here, and elsewhere. I cleaned the bowl float, I found a port gasket with a little flap that was glued stuck, maybe something that happens when a motor is left bone dry in a garage for a long time. I washed all the parts in SeaFoam, and added a little to the gas. Finally I added a small in-line fuel filter to the fuel line between the tank and the carb, because it had none before. I also took lots of cell phone pictures along the way in case I didn't remember how it came apart and went back together.

I still don't know which of those tinkerings fixed it, but I put it all back together and now it runs great ever since. Don't be afraid of a carb overhaul, it's not as complex as it looks. Great sense of accomplishment, increases your skill range. Be brave, do it!

A lot of the time it's in the fuel, especially outboards. A little splashing around and you get a little water in through the vent on the tank. Over time it accumulates and then starts forming crap in the tank, next thing you know one of the jets plugs up. I now carry a can of carburetor cleaner in my tool box on board, just in case. Some folks put an extra filter in the fuel line between tank and motor to head that off. If I lived aboard, I would do that. I use my kayaks for almost all of my excursions rather than my dink, so I haven't done that (yet).

ETHANOL! Bane of all small gas engines. When ethanol fuel is exposed to the atmosphere, it absorbs moisture. The moisture causes phase separation when the mixture reaches the saturation point and comes out of solution, forming a milky substance that is of higher viscosity; it won't flow through the metering jets in a small outboard, it can plug filters, and the longer it sits, the gummier it becomes. Additionally, the ethanol component can become corrosive, and fiberglass fuel tanks constructed prior to 1993 can experience structural failure as a result of ethanol breaking down the resins.

Ethanol is the worst thing ever to hit the marine industry, a recipe for disaster. With ethanol fuel, and particularly the vented fuel systems typically found on our small outboards, it's ripe for problems. Auto systems have closed fuel systems, and aren't susceptible to the moisture ingress that fouls the fuel systems in marine applications.

I'd be willing to bet your problem is slime in the main jet. The best way to correct it is to remove the carb, disassemble it and clean it with carb cleaner. If you're careful, you can probably R&R the carb without having to replace any parts. Resist the temptation to short cut the job, if you don't get down to removing the jets and cleaning all the small passages with carburetor cleaner, no worries, you'll soon have another opportunity to do it again! AND, if you continue to use ethanol fuel, you'll become adept at carburetor cleaning!

If you clean the carb, flush out the ethanol fuel, and never use ethanol fuel, you'll likely never have problems. If you MUST use ethanol, add a Racor 025-RAC-02 in-line filter, it will help to separate any water. Use an additive like PRI-G, and don't store fuel for more than a month or so, and remove ALL the fuel during extended storage.

If you are in an area where non-ethanol fuel is hard to find, check out pure-gas.org for sources for it. I eliminated ethanol from my outboard some time ago, and can attest that it has eliminated the problem, and can also attest that just the use of a small amount of ethanol brought the problem back in short order.

Maerin said:

ETHANOL! Bane of all small gas engines...

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Yep, that too. I'm sitting here in the middle of corn country where millions (billions?) in tax money are spent to subsidize the evil stuff, and I don't go anywhere near it. And if most corn farmers were honest, none of them use it either. They have additives now that claim to neutralize the damaging characteristics, but it's much better to search high and low if you have to, to find the "real" stuff - liquid dinosaurs, not cornflakes. Entirely aside from its effects on rubber fuel lines and gaskets, I think it's more than just my imagination that the real stuff runs far more smoothly and starts easier.

Lots of good advice and everyone is on the same page.
Clean the filter.
Get the tank completely empty.
Use fresh non-ethanol fuel.
Like meridian said, toss in some Sea Foam and use it regularly.

Yes ...
SeaFoam is great. In the 50's it was Risaline or Risalone.
When I was a young man I'd bring old discarded froze up outboards back to life w Risalone. I'd put it down the carb throats and through the plug hole. Then let it sit for several days. After a bit of work w the big wrenches I'd be buzz'in up and down the slough w the revived OB engine ... the pistons and the rings both freed up.

I have an 87 Nissan Stanza w 281000 miles on it that I got from the original owner and the receipts show the garage put Risalone in at every oil change. And as far as I know Risalone or Risaline is the same as SeaFoam.

We get our ethanol free gas from a farmers supply.

On the advice of a lot of outboard mechanics this is what I add the gas to clean out and keep clean the fuel system on all brands of outboards.

Quickleen Mercury Quicksilver 12oz.

One trick to use is if you have a spin on type inline fuel filter is to empty the filter of gas and fill it with cleaner. Then pump it to the engine so the fuel system gets a strong flush of cleaner right off the bat.