OUtboard dies after 25mins? Please Help!!!!!!

[120379]

Hi everyone,

I have just recently purchased a 14ft Marina speedboat with Yamaha 55ae 663 engine on it. Nice tidy boat except the engine cuts out after about 25mins of use. Then letting it sit for about fifteen mins the engine will eventually start again and then we take it back in. Checked the fuel filters and found a lot of water sitting in them. One after the tank had about 75% water in it. And the one in the engine had water in it as well. Flushed these out and put it back together. Took it out again and it ran fine for about 25mins again and just died. Paddled over to a buoy and waited for about 15 mins then got it goin again with fast idle on. Took it back in. It appears to pump water very well, and has apparanly been recently serviced.

Any ideas whats goin on??

I am goin to strip the fuel tank and drain it thoroughly to make sure there is no more water in there. And also empty the carbs.
Hopefully this will sort it out.
Any advice or ideas welcome!! Bit of a dampner on the heat wave coming! Want to get out in her!!

 

[Dipper]

Just an uneducated guess but could it be a partially blocked breather to your tank? As fuel is used a vacuum will build up until it stops fuel being extracted. When you wait 15 minutes, air is slowly drawn into the tank to relieve the vacuum.

 

[silver_boy]

Yeh, I was thinking this aswell as I was reading the post. If I ever forget to open the vent in my 3.5hp outboard it will run for a few minutes then cut out due to the vacuum.

 

[capnjack]

Is there a breather valve on the tank? The most common source of outboards cutting out is due to the breather plug on the tank not open.

 

[120379]

Thanks for the replies, was going to mention the breather but i was tryn to keep it short. The breather is just infront of the screen on the right side it is a bit crusty but i believe it allows air through as if you put your nose near it you can smell the petrol well enough. But the position is a bit worrying. It may get a bit too much splash on it. Where are the breather holes normally situated? Cheers Adam

 

[Dipper]

I'm not familiar with the set up on motor boats but you can check the breather fairly easily. IF IT IS SAFE TO DO SO unscrew the filler cap as the engine dies. If the engine picks up/cuts in again, then it is a breather problem. You may also hear a hiss as air enters. If removing the filler cap has no effect, then that is not the problem!

 

[Lakesailor]

If you're finding water in the fuel, that is prime suspect. As you've only just got the boat it's hard to tell if it's condensation build-up.
If you leave the breather open when not using the boat warm air will be drawn in as the boat cools down on an evening and the warm air will condense in the cooler fuel tank. This condensed-out water builds up. If you never clean out the fuel tank it will build up until it's deep enough to reach the tank outlet. Until you completey evacuate the tank you will never get over this problem.
If the tank is not removable you will need to siphon everything out. You can separate out the fuel from the water and use the fuel again.

Don't have a fag-break whilst doing this.

 

[andyball]

is there a spark at the plugs after it's died & won't restart?

 

[longjohnsilver]

Maybe the fuel pipe is collapsing under load and therefore restricting the fuel flow. Stop and it returns to its normal shape untill the whole process happens again.

Or maybe the fuel pick up pipe is collecting some crap in the tank and when you stop it drops off and gets sucked up again when you restart.