starting a flooded 4-stroke

[Megunticook]

Yesterday out with my son getting him ready to take the boat out himself.

Ran the outboard (2008 Yamaha 4-stroke, diligently maintained) for 15 minutes heading out, sailed for 30, then headed back in. Son pulled the choke out, wouldn't start. I figured it was flooded so pushed choke in and turned throttle down to idle, wouldn't start. I let it rest with the choke fully open (knob pushed in) for 15 minutes or so to let the excess fuel vapor evaporate, then it started.

First, am I correct in concluding that the carburetor was flooded?

And second, is there a trick to quickly starting a flooded carb or do you just have to wait?

On an old vehicle I would make sure the choke is open and put the accelerator to the floor in order to fully open the throttle valve, then crank. Should I have fully opened the throttle valve on the outboard? For some reason didn't occur to me to try that.

Good lesson for my son, although I think it made him nervous about starting the outboard. I told him key is just to stay calm and eliminate potential problems one by one. Worst case scenario (drifting down on rocks or boats), deploy the anchor if you can't sail out of trouble.

Will definitely be an exercise in parental trust when I let him go out without me.

[kerrydeare]

... First, am I correct in concluding that the carburetor was flooded? And second, is there a trick to quickly starting a flooded carb or do you just have to wait? ....

I'm far from expert, but my own Tohatsu sometimes performs (or un-performs) this way. In most such cases the carb was not flooded, but I learned along the way that there are quite a few tricks.

Once another fellow jumped into the dinghy, turned the throttle all the way to full with no choke, and "slammed" the starter cord mightily until the beast started. He was a lot stronger than I in such tasks, and it worked. Another idea if indeed the carb actually is flooded is to shut the fuel valve and keep pulling the cord until the excess fuel in the carb is gone. This is not a particularly good idea environmentally, but it has worked for me in the past.

My point in the above is that the instructions in the user manual sometimes have to be abandoned and other seemingly incorrect procedures tried.

[Megunticook]

Once another fellow jumped into the dinghy, turned the throttle all the way to full with no choke

I suspect this is the most effective tactic--by opening the throttle plate fully with the choke wide open, it should allow more air to enter the combustion chamber and clear out the too-rich fuel mixture. In theory, anyway, I'll have to test this out while on the mooring sometime.

Another idea if indeed the carb actually is flooded is to shut the fuel valve and keep pulling the cord until the excess fuel in the carb is gone.

That also occurred to me, although it seems like it would take a while to empty the carb bowl and fuel line, and would produce a whole lot of unburned fuel vapor that would just enrich the mixture even more until you run everything dry and are just pulling in air. Then you'd have to open the fuel line again and pull the starter to fill the line and carb. bowl back up before it would run.

You know, what are we even doing running carburetors anymore? That's like early twentieth century technology! I would love to replace my motor with an electric one that starts with the flip of a switch...but that's quite an investment by the time you upgrade your battery bank, buy the new motor, etc. Still, maybe for 2021...

[kerrydeare]

... what are we even doing running carburetors anymore? ... I would love to replace my motor with an electric one that starts with the flip of a switch...but that's quite an investment by the time you upgrade your battery bank, buy the new motor, etc. ...

You probably know of Torqueedo. Unfortunately what I've read over time was ultimately not positive about the system. I'll spare you the details. Meanwhile except for small trolling motors, there seems little to choose. We are still burning the fossils.

[casampson]

I don't know anything about starting a flooded outboard, but perhaps your original problem was caused by pulling out the choke when the engine was still warm. Considering that you had already run it for fifteen minutes, and that only 30 minutes after that had elapsed, I'll bet it didn't need to be choked at all. I know that my 6 HP Evinrude reacts very negatively if I pull out the choke even after an hour has gone by.

[kerrydeare]

I don't know anything about starting a flooded outboard, but perhaps your original problem was caused by pulling out the choke when the engine was still warm. Considering that you had already run it for fifteen minutes, and that only 30 minutes after that had elapsed, I'll bet it didn't need to be choked at all. I know that my 6 HP Evinrude reacts very negatively if I pull out the choke even after an hour has gone by.

This is often my experience with the 3.5 Tohatsu.

[wikakaru]

I used to always start a cold engine by with choke and a warm engine without choke as per the manual. I don't any more.

When I bought my new Yamaha 2.5 a few weeks ago the technician giving me the pre-delivery briefing said to always try and start it first without choke, even if the motor was cold. Choke was only needed if it couldn't be started without the choke and using choke straight off the bat would flood the carburetor.

Along a similar line, I purchased a new chainsaw earlier this summer, and couldn't get it to start following the owner's manual procedure. One of my buddies who uses chain saws all the time couldn't get it to start either. I took it to a factory authorized service center that checked it out and said it was "severely flooded". The service center said the owner's manual starting procedure was "guaranteed" to flood the carburetor.

I did some internet research after the chainsaw incident, and it looks like the procedure to unflood a small engine is to turn the choke off, set it to full throttle, and just keep pulling until it starts.

I wouldn't think that turning off the fuel valve would be very effective. There is a lot of fuel in the fuel line and carburetor bowl. When I intentionally run the engine dry at the end of the season it takes quite a while for it to die after the fuel is shut off. Pumping that much fuel through by hand would be almost impossible.

To my knowledge the smallest fuel injected outboard available is the Suzuki 9.9. It takes two pulls to start: one to generate enough electricity to power the EFI unit, and the second to start it.

I'd love to see EFI on every outboard. Small carbureted outboards already have problems with E10 gas. The push to go to E15 fuel everywhere all year long will only make things worse.

Smooth sailing,

--Jim

[Megunticook]

I researched electric motors last year and figured I'd be out roughly $3K including new batteries. Looked at Torqueedo but was leaning toward Elco. Local mechanic says Elcos rust out quick--but so does most anything that sits in Penobscot Bay all season!

Yes, using the choke when the motor was still a bit warm was the problem. Next time that happens I'll open up choke and try starting it with wide open throttle. Waiting a bit also works.

The Yamaha F4 I have always starts on 1 or 2 pulls--choke closed when cold, then immediately push it in halfway until it warms up. When warm it starts right up with choke open.

I rebuild the carb. every spring and make sure it's clean as a whistle, and only use alcohol-free fuel. It's been very reliable. I just think it's odd that we're still using carburetors like our grandparents did. Time to move on to better technology.

I know a lot of people have terrible, chronic issues with their outboard carbs. Doesn't take much to get them out of whack.

[John Stone]

I just think it's odd that we're still using carburetors like our grandparents did. Time to move on to better technology. .

Some people seem to really like the torqeedo. For most of us they are too expensive with a range that is too limited. The potential is there though depending on your needs.

Regarding carbs. I have a lot of respect for simple carb technology. The average person can take them apart and clean them up and almost always get them working. Maybe not as reliable as fuel injection but easily repaired. Not important everywhere but can be important so I think they still have their place. Fuel injection Leaves you few options. Pretty much have to replace it. Non ethanol fuel is essential to maintaining carbureted engines.

From a lifetime of running outboards. If cold, choke on, very little throttle. If it’s warm or been run in the last couple hours...may even all day depending on the temperature, no choke and a little throttle. If you flood it, no choke, throttle wide open. Start pulling.

This above has pretty much worked for me for two and four strokes. Some engines are a little peculiar and you have to calmly figure them out.

My generation and my parents generation grew up with carbs and I think had/have a better feel for troubleshooting these kinds of things than the current generation who has not had to learn these skills.

In much of the world carburetors still rule the day.

[Dick Kobayashi]

Not to ask too stupid a question, but what does flooded mean in the context of this discussion. A carb bowl only holds so much fuel, so it can,t be over full. Does flooded mean that a too rich mixture is in the cylinder? If so a couple pulls with choke open should solve that I would think. Does too rich mean too rich to be ignighted by the spark? A little m ore detail would be helpful. The vital organs of an ob have always been a bit of a mystery to me.

[Megunticook]

Does flooded mean that a too rich mixture is in the cylinder?

Yes.

If so a couple pulls with choke open should solve that I would think.

This didn't work for me. If the throttle plate is also fully open, though, in theory it will allow more air into the combustion chamber, thus making the mixture less rich. I still haven't tested it but will do so.

Does too rich mean too rich to be ignighted by the spark?

Correct--has the be the right ratio of oxygen and gasoline vapor for the spark to ignite the mixture. At colder temperatures, a richer mixture is required.

[mgphl52]

Correct--has the be the right ratio of oxygen and gasoline vapor for the spark to ignite the mixture. At colder temperatures, a richer mixture is required.

That's the key phrase! As "flooded" usually means wet and no vapor.

[Kilgore]

On my Tohatsu 6, sometimes the trick that works is manually emptying the carb bowl and starting over.

FWIW I run mine dry after every trip.