Mariner 2-stroke starting problem

[Paramotorgreg]

I have an old (1998?) Mariner 3.3hp 2-stroke outboard and normally it is very reliable - it starts on 1st or 2nd pull and then runs smoothly. However we are now in Greece and I have discovered that the high temperature here means that the engine will start ok in the cooler mornings and evenings but it will not start at all in the heat of the day. I assume that this is because the carburettor needs to be changed to allow for less dense and therefore less oxygen-rich air when the temperature is 32c.

I inherited the engine when I bought my boat and have no manual for it. I have searched online for a manual but can't find one. Does anyone know if my theory regarding the carburettor setting might be correct? If so, do you know how to adjust the carburettor on this engine and what adjustment I would need to make for warmer conditions?

Alternatively, does anyone know where I might be able to find a manual for this engine?

Many thanks in advance for any help.

[robinco]

I have a 1989 Mariner 4hp 2-stroke that's just the same engine as the Yamaha 4hp, only branded with a different name. Yamaha parts work fine on the Mariner.

Don't know if the same is true for 1998 3.3hp motors but perhaps could be worth investigating.

[a64pilot]

I serious doubt it is so finely tuned that it needs resetting for hot weather.
However I would not be surprised if the carburetor needs cleaning. I’d start there.

[nigel1]

If you drop me a private message and let me know an email address, I can send you pdf copy of manual.

[Lepke]

I have a 2hp and it's always a fuel issue. Usually from not using a conditioner, but also from buildups on the internal carb parts. I went to electric.

[Bill O]

Very simple motor and agree should clean the carb first. When you dump the carb. bowl of fuel collect and inspect it for water. Clean main jet and make certain float is working properly.

Also check for crud/water in the shut off valve bowl/screen. If lots of stuff in the valve bowl/screen inspect the tank for crud.


Bill O.

[mikedefieslife]

The 3.3hp is the same as the 2.5 just with a different carb slider and slightly different final drive ratio. I have the 2.5 that I swapped the slider for a shorter one to effectively turn it into a 3.3

On cold days it starts well, left sitting in the sun in 30 degrees (I'm in Greece too), it starts well. Slightly over fuel the carb, and it's a bitch to start.

I should add, always bring it to a stop by letting the carb run out of fuel and not using the emergency stop. When I use the latter I sometimes have to pull it a few times with the fuel off to drain the carb, then start it normally.

[bourque]

It's humid there. So at night when the air cools, it may be sucking air into the fuel tank and condensing water, which drops to the bottom of the tank near the inlet. Try adding drygas (mainly methanol) to soak up the water. Also, put a white towel over the tank and gas lines to the motor. The hot sun may be cause the fuel to boil. Lastly, get some spray starter fluid and spray it directly into the carb when starting.

[Paramotorgreg]

Thanks for your comments and advice. Sorry to trouble you again, but the general consensus is that the problem is most likely to be caused by a dirty carburettor and I should clean it. I have been looking online for instructions on how to dismantle and clean the carburettor, but so far without success - can anyone suggest where I can find this information?

[mikedefieslife]

If you are in or around Nidri/Vliho I don't mind giving you hand with the carb. Of course you might be somewhere else entirely though.

[stormalong]

From the description it sounds like a Tohatsu. They have been sold as many different brands. I have has a few of them over the years.



The carburetor is very simple and easy to clean. I have to clean mine every spring. Just take it off the engine and take it apart. Don't loose the float valve needle - some versions of these carbs have it attached to the float arm, some don't. They do not sell parts for these - only whole carburetors.


If you are careful taking it apart you will see how simple it is. Only four internal parts. Float, float lever arm, lever arm pin and needle valve.

[Calaban-Alleria]

Hello Paramotorgreg: As others have said - most likely carb issues - from years of running two stroke motorcycles it is almost always carb issues. Don't be afraid to remove, dismantle and clean the carburetor without a manual its not that hard.

You just need a good clean place to work. Buy yourself a spray can of automotive carb cleaner. Nasty stuff, wear gloves, have good ventilation, but it works. Take pictures at each step. Clean the outside of the carb completely first.

Then start disassembly, cleaning and laying out each part in order on a clean shop towel. Try to be sure to spray the carb cleaner in all the small passages of the carb (watch out for splash back - wear safety glasses is a good idea). When everything is cleaned and blown out with air start re-assembly. If you have laid everything out methodically it should go back together easily (with no left over parts - that why: take pictures at each stage).

Also don't forget the gas tank - don't mess around - you just spent too much time getting that carb pristine to take a chance on re-contaminating it with the old gas and crud that may be in the tank only to have to repeat the cleaning (an early lesson I had to learn the hard way). Dispose of the old gas and insure that tank, and any filter screen in the shut off is also clean. While your at it give it a new spark plug for good measure.



Good luck.

[Bill O]

Originally Posted by Paramotorgreg

Thanks for your comments and advice. Sorry to trouble you again, but the general consensus is that the problem is most likely to be caused by a dirty carburettor and I should clean it. I have been looking online for instructions on how to dismantle and clean the carburettor, but so far without success - can anyone suggest where I can find this information?

Send Nigel1 (post #4) a PM and he offered to send you a copy of the manual. Generally these are step by step descriptions on how to remove, inspect/clean and reassemble the carb.


Bill O.

[Bill Seal]

A dirty carb doesn't explain starting and running OK when the weather's cool but not when it's hot. A flooded crankcase would. As mentioned above, just try turning off the fuel before stopping it.

[a64pilot]

Originally Posted by Bill Seal

A dirty carb doesn't explain starting and running OK when the weather's cool but not when it's hot. A flooded crankcase would. As mentioned above, just try turning off the fuel before stopping it.

A leaking needle valve, mal adjusted float or fuel in a float would all lead to flooding though, and would be found in a carburetor cleaning.
Although I agree on turning the fuel off, I always treated my old two strokes like airplanes, you turn them off by running them out of fuel.