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Butterfly Choke Valve

J

jdbun1234

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I believe that is what they ar

I believe that is what they are called. I have a 78 model 70 hp evinrude and they are stuck open. I can manually close them but when I shift into neutral they will not close automatically. Any suggestions as to why this might be happening? Thank you
 
"Your post is somewhat confusi

"Your post is somewhat confusing, however.....

The butterflies at the front portion of the carburetor(s) are called "choke butterflies".

They are only supposed to close when you engage the choke switch.... toggle switch or pushing the key in, and should spring fully open otherwise.

Open is when they are fully horizontal. Closed is when they are blocking the carburetor throat."
 
"okay, so they should be open

"okay, so they should be open unless I am trying to start the engine. Once the engine is running they should be full open??"
 
They should alway be fully ope

They should alway be fully open unless you're engaging the electric choke switch.
 
"Joe, took the boat out on the

"Joe, took the boat out on the water today..basically doing the same thing..still bogs down under load, rebuilt carbs and replace the fuel pump, new lines...is it possible its a vacuum leak of some kind??? Thanks"
 
"The following assumes that yo

"The following assumes that you have checked the compression and spark and that these two areas are as they should be.

When you rebuilt the carburetors, did you manually clean the 3 high speed jets?

Bogging down when throttle is applied is normally caused by fouled carburetors, a sticking timer base under the flywheel, or having the throttle butterflies opening too soon.

There should be no tension on the linkages between the carburetors, that is all of the butterflies should start to open and close at the same time. And at idle, all should be closed, not 2 closed and one slightly open.

The timer base should (engine not running but in gear) move smoothly from the idle position all the way up to the full spark advance position where the timer base would be up against the rubber stop on the full spark advance screw.

The throttle butterflies should just start to open when the scribe mark on the cam is dead center with the throttle roller, not before or after.

When time permits, visit my eBay store at: http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
 
"I am not sure what you mean b

"I am not sure what you mean by "Bogs Down"...is it a smooth loss of power or a jerky type of miss?? A smooth loss of power generally indicates a lean fuel condition...this can be verified by squirting some gas/oil into the carburetor when the motor starts to slow down...if the RPM's increase, it shows there is a lean condition usually caused by clogged carburetor jets, a bad fuel pump, clogged fuel filter/fuel line etc. As Joe explained, If the timer base is stuck, the timing will never advance fully and the motor will be smooth but lack top end power. The throttle roller synchronization is also critical. It is hard to do any of this without some type of service manual. It is also important that the gas is fresh and not left over from last year."
 
"Let me clarify "Bogs Down

"Let me clarify "Bogs Down", when I put it in gear it just dies..so I guess bogs down would be wrong in that respect."
 
"Bogs down means that the engi

"Bogs down means that the engine would have a tendency to die out, or actually die out and stop when the throttle is increased.

Having the engine actually dies out as soon as one puts it into gear is just that, the engine dies whwn put into gear.

Check compression and spark."
 
K i was wondering on my 1980 70 hp Johnson Had the carbs rebuilt it is a 3 cylinder and my tropd carb is not opening or shutting all the way either direction
 
Vanttam said:
K i was wondering on my 1980 70 hp Johnson Had the carbs rebuilt it is a 3 cylinder and my tropd carb is not opening or shutting all the way either direction
Click to expand...
You need to perform a Link & Sync on your carbs. The video I've linked below will give you an idea how to do this. Also, be sure the plastic sleeves are present on your throttle cam rollers, otherwise the carb butterflies will not be opening at the proper timing in the ignition.

A final FYI, it's best to start a new thread to troubleshoot your problem. You have commented on a 15 year old thread and it's easy for this to get lost on the forum.

 
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