thevoyage

Outboard shuts off - fuel tank sloshing

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Hey guys I was taking my tender out in the bay and the engine shut off a few times when I got into small swells. On a calm lake it was running fine the entire time except when I ran over wake and it threatened to shut off.

Its a 6hp tohatsu 4 stroke, 3 gallon west marine gas tank. Seems like others must have experienced this problem?

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No idea....

overheat sensor on many motors triggers shut down

A dirty fuel system is always worth considering 

the kill switch device is worth looking at 

Ive never used a four stroke...oil level sensor ?

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Have a look at the tank. The EPA mandates that gas containers NOT be vented these days. So the tank swells from the pressure and the pickup tube isn’t in the right place.

 

if you have an in-line demand valve between the tank and the engine that can also be problematic. But don’t just take that off without venting the tank in some way; see above pressurization issue

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The pickup for that stupid outboard (had one and hated it) is well above the bottom of the tank. Add a bit of chop and no fuel.

Keep the tank 1/3 full or more.

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The classic way to spot a fuel delivery issue is the squeeze the primer bulb as the engine begins to falter...force feed the motor. 

modern American gasoline is full of corn...this alcohol can cause plenty of dirty fuel problems  .  Check for corn cobs growing in your tank, fuel filter, carb ...

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Unlike Zonk, I liked that engine when I owned it. Like Zonk, I hated that tank. I kept it topped up so I didn't have the high pickup issue but I found I had to religiously remove the fuel line after use or the tank would bloat in warm weather and drive fuel into the carb, leading to flooding every single time I came back to the boat. 

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I have the same engine circa 2007. Currently shows 250 hours. My 3.1 gallon tank is vented, via a small, round, threaded vent, centered in the fuel gauge. It is not labelled and not mentioned in the instruction book. Turn left to open vent. It looks like Tohatsu is still selling the same tank on their webpage/catalog, so you might have a vent. If messing with the tank doesn't help, I would pull the cover and give the engine a good look over. Check all the connections, look for loose wires, etc. It could be electrical, but I suspect it's fuel delivery. The problems with my Tohatsu (except for a leaking prop seal) have ALL involved the carb. It would start and idle, rev in neutral, but would not rev in gear. I've pulled the carb 2x and flushed/cleaned it. The orifices are prone to clogging easily, even with a fuel filter in the line. 

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The carb would clog if it you looked at it with slightly squinty eyes...

It would also clog if the day of the week ended with a "Y"

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Mine had the threaded vent too. If you leave it open when not in use, you get water in the fuel, a clogged carb, and a short shelf life due to volatiles escaping. If you close it, you get pressure-driven fuel past the needle valve and flooding when you come back to the boat. My solution included ethanol-free gas, disconnecting the gas line and shutting the vent between uses, and keeping the tank topped up. With that, it served me well.

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20 hours ago, thevoyage said:

Guys it's the external 3 gallon tank. That tank is also airtight however

Air tight? You must have a vent, right??

It is a fuel delivery problem. Make sure you take the motor/tank to a proper mech once a year to clean the crap out left by the new gas formulations.

California has far reaching tentacles. 
After running my OB, I flush with Freshwater and run the Carb/fuel injectors dry. Then I manually run some Carb cleaner through the fuel system.
I have to  do this because the fuel volatile's will dry up and leave a residue that will need a breakdown to clean. It can hang up  your fuel delivery system.

The fuel of your father's is not the fuel you run through your OB.

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unplug fuel line -let carb run dry-later plug line in -no deposits in the carb jets-no overpressure to flood engine

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On 1/10/2018 at 4:14 PM, thevoyage said:

the engine shut off a few times when I got into small swells. On a calm lake it was running fine the entire time except when I ran over wake and it threatened to shut off.

 

bet there is water in the bottom of the tank .

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9 hours ago, Mid said:

 

bet there is water in the bottom of the tank .

Guys this is a brand new gas. Along with a little bit of carb cleaner for good luck. The gas tank is very much air tight as well

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I would say the carburetor float and/or needle valve are not set properly. Bouncing around makes the needle valve stick in the orifice, because the level in the float bowl is too high, or because gunk is keeping the needle valve in place too long. Then the engine starves.

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