Carbs stuck on closed position???

[bretmoua]

Ok, so after rebuilding my carbs, the motor is reving like crazy on startup even though it's on neutral. I rechecked and even rebuilt it again for a second time and everything is nice and tight and all hoses are where they should be with zip ties. Carb link is attached as well as oil pump link.
When I choke my motor, it just makes a clicking sound and the butterflies in the carbs do not open or close at all. Does that mean my butterflies are stuck in the close position? Can that also be a reason why my motor is reving like crazy on startup? Please help guys...It's been almost 3 weeks now and I'm getting frustrated.
Again this is for a 1996 mercury xr6 150hp outboard 2 stroke motor.

 

[scottmm73]

Re: Carbs stuck on closed position???

Pictures of the carbs please. If I am understanding you correctly the choke plates are closed right now? They should be open. If this is the case you have reassembled the carbs wrong.

 

[Chris1956]

Re: Carbs stuck on closed position???

That motor does not have a conventional choke. When you push the choke button, a solenoid valve opens and fuel gravity feeds from the top carb into the throats of the mid and lower carbs. I am not sure why she is revving up. Some of those motors have a thermovalve in the water jacket. It has a tube from the carbs, and allows the motor to rev up a bit, when it is cold. Maybe your hose is off, or the valve is broke? Maybe the idle stabilizer is malfunctioning? What is the idle timing advance?

 

[keith2k455]

Re: Carbs stuck on closed position???

If your choke plates don't move, there is a problem with how their assembled. If they are working OK, you may just be hitting high idle circuit, designed to work that way for cold start. when you say engine is revving, how many RPM?

Another cause of rev like that could be a vacuum leak. Check to make sure all your ports are connected and plugged correctly.

 

[bretmoua]

Re: Carbs stuck on closed position???

Here's a picture of my top carb. All 3 carbs are currently sitting in this position. Should the butterflies be open? It's reving up to almost 4000 rpm on initial startup. I'm not keeping it on for more than a few seconds with water running because of the louder than before rev of the motor. Please help.

 

[keith2k455]

Re: Carbs stuck on closed position???

I would think that either your idle circuit is set that high or you have a vacuum leak.

 

[EpOcH]

Re: Carbs stuck on closed position???

With the butterfly's closed that is idle when they open (more air would induce more fuel) the rpms would rise.

 

[bretmoua]

Re: Carbs stuck on closed position???

How would/could more air get in when my butterflies are closed off like that?

 

[EpOcH]

Re: Carbs stuck on closed position???

See the hole in the 'top' of the butterfly, that helps give the engine air at idle when the blades are closed, looking at the pic your blades are slightly open, you may find that you just need to back off the idle adjustment screw if you have one that is holding those blades open, if you adjust them so they are fully closed and your getting 4000rpm still then air is coming in elsewhere (i.e. as mentioned above air leak in the form of a vacuum leak) or something else is telling it to idle that high, i.e. the idle circuit.

When those butterfly's are opened up (horizontal compared to the vertical position they are in the photo) more air would come in , which would mean more fuel will be sucked through which would mean RPM will rise and power would increase.

Chris1956 above seems to know about your particular engine/carb setup what I mention above is just basic engine mechanics.

 

[Dukedog]

Re: Carbs stuck on closed position???

There are NO choke plates. It has an enrichner system. Try this. Disconnet tha throttle cable from tha throttle/advance arm. Take tha linkage that connects all three carbs completly off and all butterflies are COMPLETLY closed. Make sure tha roller on tha bottm carb is clear of tha throttle cam. Make sure tha throttle/advance timing arm is against tha stop aginst tha block and doesn't move. Start n see what ya got. If it still revs to high you have eliminated any carburator "linkage" problems. Now you can start lookin' at air leaks, idle timing (first thing I would look at) or just plain carburator problems.