[MoonShadow]

1992-2000 | 2-Stroke | 6 Cylinder 2507cc | S/N 0D082000-0T105314

[emj]

1990 up | 2-Stroke | 6 Cylinder 2327cc | S/N 0C221500 up more

[Pascual99]

1990 up | 2-Stroke | 6 Cylinder 1999cc | S/N 0C221500 up here

[Hariposter]

With kind advice from this forum I've become fairly adept at dismantling and cleaning my carb in a Mercury 3.5. Anyhow although it guns and starts fine I have two issues.

[John Doe]

I've tried bending the little metal flaps so that when he float is up it pushes against the needle and when it's down allow the needle to drop a bit. I suspect I need to be more precise than this but wondered exactly if there was a way to know how much angle to set them at? [links]

[diggler]

2. When I turn the outboard off but leave the fuel tap open it floods itself. Again probably float not adjusted and therefore not quite blocking the fuel off when chamber empty.

[mico]

Outboard motor sneezing is an audible result of a lean fuel mixture resulting from problems in the carburetor. Described variably as a sneeze, cough or stutter, an outboard motor or any engine will lose its ability to run smoothly if it does not receive enough fuel. In small engines, the culprit is the carburetor. On modern automobiles a fuel injection system has replaced the carburetor. However, small block engines, such as those used for outboard motors, still use carburetors as a part of their fuel system. When the carburetor fails to provide the correct mix of fuel, the outboard motor will no longer run smoothly.

[ConfusedEnthusiast]

Improper fuel storage is the biggest cause of gunky build-up in a carburetor. Gasoline is a highly volatile liquid and even storage for a few weeks can cause significant evaporation. In particular, evaporation from the float bowl of the carburetor leaves behind a gum-like substance that can break off and clog up the injector needle as well as other parts of the carburetor, reducing the amount of fuel that can reach the engine for combustion. [links]

[Zenchess]

When an engine receives too much gasoline, it is described as running rich. The engine is flooded with gasoline and not enough air to allow combustion. However, when an engine receives too little gasoline, it is described as running lean. When the injection port from the carburetor becomes damaged or clogged by foreign material or general wear, the engine becomes starved for gasoline. Pressure build-up along the gasoline line will intermittently cause gasoline to spray into the engine causing the stuttering or sneezing effect from sudden combustion.

[RichardG]

Once you have ruled out the fuel pump, it’s time to look at some other options. Commonly operators use bad gas or have a failing fuel filter. [links]

[jonathan]

This unit holds the fuel pump and filter.

[paulineh175]

On some designs. The fuel pump is driven from the pulses of the crankcase or from a rod that is driven by the crankshaft. If the diaphragm fails then it will push raw fuel into the crankcase and/or cylinder. more

[otalesak]

When the cylinder leaks, the pump pulse signal isn’t strong enough to get the right amount of fuel to the cylinder.

[Klintel]

To determine the best speed for your boat, you want to listen to the sound of the engine. When you hit that sweet spot, the engine vibrates less and quiets down. here