Mercury 9.9 no power

[vildric]

Hi!

My mercury 9.9 4 strokes 201p has a bad idle and no power.

To start it, I need to choke, put in gear at high rev and then push the choke, otherwise it stall.

Sometime, even with the choke the outoard will stall when put in gear or idling.

But my main problem is that there is no power at any throttle position. Even at WOT the motor run very slow like if it was idling.

Sometime, if I let it at WOT a couple of minutes, the outboard will kick in, power will come back and it begin to work properly at every throttle position, but once I stop it the problem come back.

I made a video : https://youtu.be/vP8sn_btwvY



The spark plugs is fine, throttle cable too. The fuel line is not twisted or cut, and when I pump the bulb on the fuel line it change nothing (so its not a fuel pump issue?) Both cylinder compression is at 98psi.


Thanks all.

 

[CharlieB]

When was the carb cleaned? It sounds like it is time.

 

[vildric]

Thanks!

Can I reuse the gasket / float etc or I need new ones?

 

[Chinewalker]

It isn't a fuel issue. More likely Ignition. Motor is running on one cylinder, picking up the second periodically. Could be a coil or power pack.

 

[vildric]

It isn't a fuel issue. More likely Ignition. Motor is running on one cylinder, picking up the second periodically. Could be a coil or power pack.

Thanks!

Is there a way to test both to identify which coil is bad, or if its the power pack?

If I understand, I have one "coil" for my two cylinders. So how to test that ?

 

[ondarvr]

If using the choke allows it to run better then there's a better chance it's a dirty carb. Cleaning the carb is easy and won't cost you anything. Small 4 strokes tend to have issues with dirty carbs very often.

 

[vildric]

I cleaned the carb today and it did nothing.

How can I test spark plugs / igniton coil ?

 

[ondarvr]

Get a spark checker and see what it does when it's acting up.

 

[tlh 178]

i had similar problems with my 2003 9.9 and rebuilt the carb w/ carb kit and fixed my problems. i did it myself and was around 35.00. when was the last time it was rebuilt? i'm no expert, but spark plug tester are only a few dollars. thats an easy test!

 

[Michawilden]

Remove your spark plugs and see if they both have spark. Probably one of them does not have spark. You can also try to pull one spark cap while the engine is running. If the engine instantly dies, than that is the spark\coil which is good. If you pull a cap and there is no change in the behaviour of the engine than that spark plug\coil is bad. Pull them with isolated pliers or else you will get a jolt. If the engine behaviour changes but will stay running you have another problem than your ignition but my money is on the ignition.