Carb dumping fuel when tilted

[ejthomp]

This is a 1983 90 hp Mariner. 6 cylinders, 3 carbs. This is my neighbors outboard, but I'm trying to help him. I've rebuilt carbs before, but before I dig in I wanted to ask for some ideas.

Here's the situation: The engine runs. Seems to run okay. I can pump up the fuel pressure using the bulb in the fuel hose and no fuel leaks through the carbs. It will build up a good amount of pressure in the line. From this I know the floats are working and seal off excess fuel from entering...

But when I tilt the motor all the way up (after shutting it off), a lot of fuel leaks out of the front of the carbs and pours in the bottom of the engine, which eventually leaks through and down around the transom area.

Before I rebuild the carbs, I'm trying to understand what could be wrong. What is supposed to keep all the stored fuel in the carbs from leaking out when they are tilted forward?

Thanks for your help!

 

[Laddies]

Re: Carb dumping fuel when tilted

Thats normal, not unlike a 3/4 full glass of water beening tilted some runs out if you set the float levels properly then the only thing that will help is to run the carbs dry or not tilt the engine.

 

[ejthomp]

Re: Carb dumping fuel when tilted

I have a 1984 70hp Yamaha that doesn't lose very much fuel when I tilt it up. I dont' even notice it.

This Mariner must dump virtually everything left in the fuel bowls. I'd guess about 10 ounces of fuel that ends up in the motor well when the motot is tilted all the way up. We're not talking a few drops, we're talking pouring out.

They use this boat for crabbing and so when they pull a crab pot, they sometimes get the line tangled in the motor and have to tilt the motor up to get it out of the way.

Are you telling me that this is normal for a Mariner of this vintage?

 

[ejthomp]

Re: Carb dumping fuel when tilted

So, if there were something to check, it sounds like it would be the float level. Maybe the floats are set higher than necessary so the fuel bowls are extra full. If I lower the floats, at least less will leak out.

 

[Laddies]

Re: Carb dumping fuel when tilted

Be sure to set the float levels to spec or the engine could start hard with low levels.