Fuel mark in water when boat in idle

Dear all,

I have notice a wierd thing when removing my boat out of water.
I start my boat from the dog and put it in idle state. Then I could notice behind the boat on the water surface some mark of fuel going out ans time to time some black stuff.

Some think that in idle the boat si not able to burn all the fuel in the carb and point me out to adjust the float of the carb. What do you think can it be this ?

In addition what could be this black trace, could it be oil ? if oil how can it be because I have no oil leakage at my engine

Thanks for your help
regards
serge

Hello,
I have completly rebuild my carb last season because I got dark smooke when bopat was in idle speed. So I bought a repair kit and change all the parts and gasket everything.

Now I do not have any more dark smoke behind the boat but only fuel mark leaking begind the boat when I am not riding and imposible to stand at th rear platform of the boat because of brown smoke and fuel smell.

In normal speed the boat engine is reacting perfectly well, no cughting, good power.

Only thing which is wierd for mee is why the boat still smoking and fuel linkage in water. and this only when I am in stop but idle.
If I put some gaz by remaining at teh dog, really brown water coming out behind.

So in order for me to understand :

1 - what should I do to avoid fuel leak in water at idle ? how to adjust those flwot if it is this

2 - Why I still have smoke behind ?
3- why does it smell fuel behind the boat in addition to brown smoke ?

Thnaks for the information

I am not a mecanician expert but with good explaination and video link I can do

I need to solve this heavy smoke and smell which is really enoying nd avoid people to stand at the back
regards
serge

Hello

I have rebuild my carb already Last season. All parts have been change with repair kit.
Son now looking at what to adjust to avoid over fuel and heavy smooke at idle

How to adujst fuel float ? Vidéo would help.
What to adjust and How for heavy Brown smooke at idle?

Thanks for help

wakespirit wrote: Hello I have rebuild my carb already Last season. Vidéo would help. Thanks for help

8122pbrainard wrote: 8122pbrainard wrote: Serge, It sure sounds like you have a rick fuel condition. Yes on the float level but also the carb may be due for a rebuild. There are some great videos on line for both adjust the floats as well as rebuilding the carb. If you can't find any, come back and I know we will be able to provide some links. Videos on 4160

If the float is not adjusted properly, then 2 things are likely to happen:

1 - Float is adjusted too high: Too much fuel will enter the float bowl and the excess fuel will dump directly into the carburetor causing a rich condition. I had a float stuck open and the engine ran very rough in the low RPM range. Black smoke poured out the exhaust.

2 - Float is adjusted too low: Not enough fuel in the float bowl. The engine starves for fuel at higher RPMs. The engine may appear to run OK at low RPMs, but sustained higher RPMs will often cause the engine to stumble and run very poorly until RPMs are lowered and fuel re-fills the float bowl chambers.

Link below to the Holley Carburetor site for float adjustment:

Link to Holley Carburetor Float Adjustment Video

One challenge with the Holley 4160 Marine carburetor, is that there is no "sight glass" window for easy fuel level viewing. This makes for some trial-and-error adjustments. One typical starting point is to remove the fuel bowl and hold the assembly upside down. The top of the float should be parallel with the top of the float chamber.

(The QuickFuel M-600 marine carburetor is based on the Holley 4160, but the QF unit has several upgrades. One major upgrade is the site glass window and float adjustment hardware on the top of the fuel bowl.)

JQ