1994 Merc 2 Stroke OB. 15hp - Idle Issues Continued...

[cmb1998]

I have ongoing issues with my kicker. Looking for a little help.

1994 Merc Electric Start - Long Shaft - 15HP.

Here are the symptoms-

1) It starts great when cold. Pull twice on primer and hit the button and starts right up.
2) If I let it run without hitting the throttle after starting when cold it will die after about 10 - 15 seconds (primer in or out, doesn't make a difference).
3) If I crank the throttle before it dies it runs great from about 50% throttle up. If I run it from 25-50% it will run rough. If I run it up to 50% or higher (from Idle or running at 25% and below) it will run rough for a few seconds then smooth out.
4) If I let it die from idle, it will not start. No matter what. Have to let it set for 10 - 20 minutes then try again. I Noticed that when I try to start it after it dies I get a solid sheen of oil / gas on the water behind the engine.
5) If I kill the engine from 50%-100% throttle it will start back up.
6) Squeezing the primer bulb at idle (I was thinking it wasn't getting enough fule) doesn't make any difference. It still dies at idle.

I had carb adjusted. No Change,
I have had the carb rebuilt. No change.
I have moved to a hotter plug. No change.

What should I try next? Is there any adjustment on the carb for the idle mixture? Are there any vacume lines or anything I should check?

Thanks,

Chris

[Starfish]

Sounds to me almost certainly like you have a stuck float or a whisker of something stuck in the float valve. It's flooding when running at idle, but at higher throttle it's burning the fuel fast enough to prevent the flooding. Test it by squeezing the bulb with the motor off, and holding it squeezed tight. If the bulb slowly deflates it's probably pumping the fuel into the carburetor- which it shouldn't do. If so, it's an easy fix, usually just something in the float valve but occasionally a hole in your float or a bad seat on the valve. Just drop the carburetor bowl, remove the float, shake it to see if it's full of gas (replace if so), and inspect the valve and seat.
Good luck!

[Lou]

Sounds to me almost certainly like you have a stuck float or a whisker of something stuck in the float valve. It's flooding when running at idle, but at higher throttle it's burning the fuel fast enough to prevent the flooding. Test it by squeezing the bulb with the motor off, and holding it squeezed tight. If the bulb slowly deflates it's probably pumping the fuel into the carburetor- which it shouldn't do. If so, it's an easy fix, usually just something in the float valve but occasionally a hole in your float or a bad seat on the valve. Just drop the carburetor bowl, remove the float, shake it to see if it's full of gas (replace if so), and inspect the valve and seat.
Good luck!
Good advise!
When you pump the primer bulb, does it deflate?
If it does check for air leaks or small hole in fuel pump diaphram.
Oil on the water behind the boat, shows it perhaps is not from
the carb (going right through the exhaust).
I suspect the fuel pump.
Let us know what you find.:)

[cmb1998]

Good advise!
When you pump the primer bulb, does it deflate?
If it does check for air leaks or small hole in fuel pump diaphram.
Oil on the water behind the boat, shows it perhaps is not from
the carb (going right through the exhaust).
I suspect the fuel pump.
Let us know what you find.:)

When I pump the primer bulb it stays firm. If the boats sits for a day or so and I go to pump it all it will take is 1/4 - 1/2 a squeeze to make it firm. Even if I get the motor running and run WOT for 5 min the primer bulb is still firm.

So if it's the fule pump, would it still not idle if squeeze the primer bulb while trying to get it to idle? Seams to me that should rule out the fule pump (I am really asking)???

Might need to order the manual and see what I can find in there. I had the mechanic rebuild the carb and this problem was present before and after the rebuild. Would a rebuild normally include new a new carb float?

Thanks,

Chris

[Boat Doc']

Try removing the carb and taking the primer cover off trhen remove the plug on the bottom. There is a spring and small ball in there. Look for the ball to be stuck in the spring or is missing. Also make sure the primer returns and is not sticking