New Tohatsu 6hp will not start

I bought a new Tohatsu 6hp Sail Pro online less than a week ago. It arrived new in the box, I filled with oil, hooked up to gas tank, mounted on boat and it cranked on the first pull. I have been following the break-in procedures to the letter and it has cranked on the first or second pull until today. I guess I have about 1 hour on the motor now. Today, I choked it and it started and would run with the choke on for about 30 seconds. I slowly closed the choke and adjusted the throttle, but I had to keep it slightly choked. After about 30 seconds, it would then rev up and quit with a puff of smoke out of the air intake. I also noticed gas dripping from the carburetor after it stopped. No matter the choke/throttle setting, it would not restart. If I waited an hour or so, it would start and behave the same. I've done this several times today and it always does the same thing.
The vent on the gas tank is open, I can see fuel in the filter, spark plug is good. I'm just baffled.

Sounds like a stuck needle/seat in the carb, causing flooding, but could be a leaky/disconnected fuel line or other similar issue. That's possibly the fuel dripping from near the carb. However, the puff/pop at the carb is typical of running out of fuel.

You are under the 3-year warranty. What does your long-distance dealer say? If it were me, I'd take advantage of the warranty.

What is the oil level on the dipstick? If it is even a drop over full, you may have excess crankcase pressure, which will blow out of the vent to the carb area.

BTW, be careful of terminology, or some may not follow your descriptions. Cranking means that the engine crankshaft is turning (as in when cars had hand cranks. Firing (and running) is something else. Pretty much any motor can crank, unless it is seized, or the start system fails (in the case of electric-start units). Closing the choke is to choke off the air... that's when you pull out on the knob. That as opposed to opening the choke, which is normal running position after warmup.

Yep. Definitely too much oil. I removed oil until the level was between the marks. The motor cranked this time and I was able to keep it running by revving the throttle a bit. I took it out for a spin and it runs fine above idle, but when I let it idle down it sputters and I have to rev it back up to keep it from dying. Maybe the oil has gummed up the carb and I should spray it with some carb cleaner?

Thanks for the terminlogy help. I'm a software engineer and deal mostly in bits and bytes.

Jazz,

I would drain/refill the oil to get rid of the diluted stuff. Spraying carb cleaner down the throat does nothing to clean a carb, though it will make the choke and throttle plates shiny ;-) As for the break-in schedule, consider yourself at hour number Zero, since the overfilled oil definitely affected ring seating. Remember that 4-strokes like to be run hot and hard. Babying this motor at this stage in its life may prevent the rings from ever seating.

If in fact the carb needs cleaning, the only proper way to clean it is by disassembling it, and then cleaning it. Perhaps you just need to adjust the idle with a shop tach. Specs are in the owner's manual, as well as the Factory service manual, available at any dealer. And there is that 3-year warranty thing... Your local dealer should be able to help you, but expect to be charged if the carb needs cleaned, as that is considered user abuse, and is not covered buy any manufacturer's warranty.

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Nothing against Internet OB dealers; They offer very good prices on "a box" that they never opened, and that makes new motors more accessible to a wider group of people. But... consumers often don't understand the nuances of the new 4-stroke motors. Long-distance guys (usually) are only interested in moving boxes, and often don't offer any pre-sale consultation. Purchase price is one thing -- cost of ownership is quite another.

This is yet another reason why dealer prep and customer consulting, available at a bricks-and-mortar dealership, even for a small 6 hp motor, is so valuable. Here is a brief excerpt of "the talk" that all of our walk-in customers get when taking delivery of any four-stroke:

1. Do not use synthetic oil. ever.

2. Use 10w-30 FC-W oil during break-in. Change after 10 hours. If running in a really hot climate, 10w-40 will be OK (but not required) after break-in -- otherwise, stick with 10w-30.

3. Check the dipstick. It is your only indicator of how much oil is actually in the motor. Never overfill. not even a drop. Half way on the dipstick is fine.

Some other tips our customers get:

Don't forget to verify LU lube level. If it's a little low, the driveshaft bearing in the LU can fail. That would be considered abuse, and may not be covered by warranty.

Never run fuel older than 30 days.

Always drain the carb (or at least run it dry until the motor stalls) if the motor will sit more than a week or two.

A water-separating 10-micron fuel filter is recommended, especially if running E-10 fuel. Likewise, if running E-10 gas, consider adding a good stabilizer, such as K-100, to every tank of gas.

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Hopefully adjusting the idle straightens out your issue.

Problem Solved

I took the OB to a Certified Tohatsu Repair Facility and they checked it over and found a very small piece of black plastic (size of a small ant) in the carb. It was preventing the float from shutting off the supply of fuel and causing the flooding, hard starting, overflowing gas issue. It had to have come from inside the OB's fuel system (carb,fuel lines) since there's a filter between the tank and the OB.

The repair tech said they had been having a lot of problems with 4 strokes caused by fuel with Ethenol - especially motors that aren't used frequently. Tohatsu issued a service bulletin about the use of fuel containing Ethenol back in 2007. I'm sure it's posted here somewhere.

Based on the recommendation of the repair tech, I plan to use Ethenol-free gas from here on out. He also recommended leaving gas in the carb for short-term storage and run it dry for long-term storage.

Cool. Your local dealer took care of your warranty issue. May have been a spec of stuff from when the fuel pump diaphragm was die-cut. Was it at no charge to you? Hopefully they performed a PDI (that your LD dealer didn't/wouldn't/couldn't do) to check everything over while they were at it.

The ethanol issue affects all OB's of all brands. The newer 4-strokes are more succeptible, as the passages are smaller to start with, so they are affected by slight varnishing more easily. Non-ethanol is better, as it won't get phase-separation problems, but the fuel quality itself is still not what it used to be. If you know that you will have the motor unused for a couple of weeks, drain the carb. If there's no fuel, it can't go bad.