Mariner 40hp 2005

I have a mariner 40hp 2stroke 3cylinder year 2005

I went for a long ride, on half throttle for about 2 hours, then drove for about 2 hours on very slow speed for fishing, then when I was going back home with half throttle, the revs suddenly dropped to about a quarter. drove for about 20 minutes and decided that it is better to switch it off.

when I took the boat off the water I tried switching it on but wouldn't keep started without the fast idle.

https://www.youtube.com/watch?v=lBJYNV96FTU&feature=youtu.be

any ideas ?

Fuel starving by the look of it.

So many things can cause that so start with the obvious/easy to check first.

Gas tank - check the pick-up (clogged/broken/fell off etc), vent on the gas tank (functioning/open/clogged with cooties etc)

anti-siphon valve (if equipped), gas hose from the tank up to the motor (connections tight, bulb working properly, clog in the line etc)

Gas hose from the connector (engine side) up to the fuel filter (clogged/broken/leaking etc)

Fuel filter (cracked/broken/leaking/clogged) - fuel line from filter to fuel pump (as above).

If all that is ok you could have a toasted bladder in the fuel pump, a clogged carb, a bad carb gasket, chipped or broken reeds, a blown crank seal, bad powerhead gasket and I'm not doubt missing a few other things that are not coming immediately to mind.

Which is why I said, start with the "easy" stuff first and keep your fingers crossed you find it before you have to start removing bolts on the engine.

the fuel line up to the motor should be ok since I connected the fuel line my spare motor to get back to shore. will start by replacing the fuel filter in the motor :S

will keep you updated .thanks.

also can I remove the fuel filter in the motor and install one in the fuel pipe from tank to motor ?

bdw forgot to tell you that I disconnected the tank where the oil is stored and I mix the oil with the fuel myself, 50:1 (quicksilver)

This morning I checked for the fuel filter but couldn't find it, I found the white plastic which I guess is a non return valve or is it the filter?
also there is a small box which I opened to check if it is in there but still nothing (marked in red)






Then I tried to start it and it was sort of not keeping the idle speed (check the below video)... please note that I didn't touch anything when it increased the revs


Then I Removed the spark plugs, cleaned then and gave them a good rub with a wire brush, left it for about half an hour and started the motor again.


does it seem to be working ok now?

also after the last video what it was working ok I removed the spark plugs and took a pic





commends are appropriated. Also if I have enough time will try and get the boat in the water to try it out.

Below from 10-15 seconds as you can see the motor is like cutting back :S

Sounds like the carbs simply need an idle mixture adjustment.

Jeff

Today I dismantled and cleaned all the carbs with some help from a friend and replaced all plugs and played some with the idle.

working much better at idle and when starint. Will try again in a few days in the water since currently wind is 18knots :/

outboard working perfectly again, thanks.