Evinrude 2 Stroke Problems

[MercMan69]

I have an older Evinrude 9.5 hp on a small jon boat.... The motor was running great, but this weekend the motor wouldn't run right, i think i had the wrong mixture. I put new plugs in and re-mixed the gas correctly at 50:1, but now the motor won't run without the choke. It runs with the choke on, but doesn't have full power. If I take off the choke it starts to run stronger, but then bogs and dies... Any Ideas?

Thanks

[Bergalia]

Sounds like fuel starvation. Try flushing your carb through with pure petrol. The jets may have a build-up of oil - or sediment. From experience (little) I've discovered that 2-strokes will accept a brief burst of pure petrol without causing harm. BUT - no more than a few seconds (15-20) of running. Then reload with correct mixture.

[ondarvr]

Just get a rebuild kit for the carb, it's very common for the jets to plug or the floats to stick. Don't run it on straight gas, it will have no effect on a dirty carb, the only thing it will do is possibly damage your motor.

[Frosty]

Take the carb off and clean out the water.

These little engines suffer badly from any water at all. The jets are so small a lump of water is like tar to these small engines.

[alan white]

Does sound like the mixture is too lean. A half-turn CCW on the main adjustment screw might solve the problem. Occasionally a little piece of something gets into the carburator and limits the flow of fuel to the jet. The engine runs high and clear but bogs down under load and won't run without choke.
If you do solve the problem by adjustment alone, but the solution is short-lived, the carburatur should be disassembled, cleaned, and reassembled with new parts from a carb kit.

Alan

[Frosty]

New parts?-- carb kit?--- These little carbs can almost be concealed in the palm of your hand. A kit could only contain a fuel bowl gasket.

I dont even think they have a mixture screw on them.

The smaller engines dont.

[ondarvr]

The gaskets on these motors deteriorate over time and this motor is around 35 years old, well past a need for a carb rebuild. Some even have a type of cork gasket around the main jet that falls apart, the small chunks get stuck in the jets. Sometimes turning the adjustment knob frees up whatever is blocking the jet, sometimes it doesn't. The carb kit is cheap and the whole job takes about an hour.

[MercMan69]

Thanks fellas,
I have a rebuild kit for the carb, I will rebuild it and post results.
I assume its a fairly easy rebuild?

[alan white]

That depends on you. Be fastidious and use good lighting. When blowing out with high-pressure air, be certain no mesh screens will be blown out--- they should have a replacement, but may not.
Floats usually have to be adjusted, meaning sight level from the side with new valve in place. If not, bend the tang that rests on the float valve.
The kit should tell you somewhere what adjustments to start with, but otherwise, start with 1 1/2 turns out and then tune.

Alan

[Frosty]

If the motor was running great dont adjust anything. Just clean it out.


Youve just got some crap in there thats all.

These carbs are constant velocity carbs --so called because (incorrectly ) the air passing under the slide and over the main needle jet is considered to be a constant velocity.

The needle jet holder has what are called emulsion mixer holes. This allows air to mix with fuel.

It is likely the main jet is blocked --so when you close the choke wich is a slider over the venturi it causes fuel to by pass the main jet and through the emulsion holes. Run it may, but not well.

[thudpucker]

You may be missing the real cause. The Fuel pump or a leaky fuel supply hose.
The problem is not likely to be in the carb. Dont touch it.

Get it going, squeeze the bulb when it starts to fail. If that fixes it (temporarily) that should tell you the little fuel pump is not working or there is a leak in a line or connection.

If you have the old style fuel pump with Six screws you can find a rebuild kit for it, but if it only has Four Screws you have to replace the whole thing.
So do some trouble shooting of the pump and hoses.

[ysots1]

hey i was reading this thread and just needed some more help. i to am having the same issue of only running with choke on. i am pulling off the carb but i think i have the lean screw way out of what it should be what is a good starting point for this adjustment.

thanks
jason

[Boatpride]

I think thudpucker is closer to the mark on this. But i expect Mercman69 has gone through the elimination process?

[thudpucker]

Originally Posted by ysots1

hey i was reading this thread and just needed some more help. i to am having the same issue of only running with choke on. i am pulling off the carb but i think i have the lean screw way out of what it should be what is a good starting point for this adjustment.

thanks
jason

If you need the Choke on to run, it usually means the Main jet is partially plugged.
Yes, take the Carb off and look into the bowl. Gunk n' some awful stuff can collect in there. Make sure the whole thing is completly free. All the jets are open. Sometimes a wire taken from a Steel wire brush comes in handy to make sure all those jets are open.

[kenJ]

E10 fuel is taking it's toll on engines. Many of the older engines have gaskets that disolve or deform in it. Water also seperates more easily causing build up of crud in carb bowls. Rebuild the carb, ensure you are adding a fuel stabilizer and try to keep fuel storage time to a minimum.