engine chokes when carbs open

[johnson_stx]

Does anyone no what would cause the engine to choke and shut off if i manually open the carb linkage arm on 175hp, basically opening the flapper inside the carbs? My other engine when this is done it revs up (rpms increase). the compression is good on all cylinders (115-110psi), the powerpack, coils, sparkplug cables, and sparkplugs have been changed and it still does the same thing. should i take the carbs out and clean them??

 

[Joe Reeves]

Re: engine chokes when carbs open

I assume that you are not actually speaking of choke "butterflies" closeing when you increase the throttle, but are simply saying that the engine dies out?<br /><br />If so, you have either a sticking timer base under the flywheel or fouled carburetors.

 

[johnson_stx]

Re: engine chokes when carbs open

yes the engine dies out. i replaced the timer base and still the same thing. if it is fouled carbs is there something i can spray from the outside of them to clean or do they need to be taken apart?

 

[Joe Reeves]

Re: engine chokes when carbs open

There are no short cuts. The carbs must be completely dismantled, cleaned thoroughly, and rebuilt. Be sure to manually clean the six brass fixed high speed jets that are located in the bottom center section of the float chambers.

 

[johnson_stx]

Re: engine chokes when carbs open

thanks for your help Joe.

 

[P.V.]

Re: engine chokes when carbs open

What year??

 

[JC1933]

Re: engine chokes when carbs open

Hi Joe, Joe i have 1995 130 hp Johnson which burnt out the little ground strap between the leg and the bottom of the couling, what could have caused this?, and is this ground realy needed? as i have a hard time locating one. thanks. J,C,

 

[JC1933]

Re: engine chokes when carbs open

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[WillyBWright]

Re: engine chokes when carbs open

Hold the phone. He's saying that if he throttles the butterflies manually, the motor dies. That's not unusual. The timing isn't matching the throttle movement. It's staying the same. To get the full effect of acceleration you have to advance both the timing and the butterflies. Otherwise the balance isn't there. I wouldn't consider that unusual. If the motor died on acceleration in the water with normal throttle lever movement, then I'd suspect a problem. But methinks he's been throwing a lot of money at a non-problem. Why one and not the other? I dunno. Maybe something wrong with the other. But probably just individual characteristics. Even twin motors don't act 100% identically. Or the other has slightly richer idle adjustments.

 

[DHPMARINE]

Re: engine chokes when carbs open

Bingo! ! But you should be able to manualy advance just throttle ( CARB )linkage itself slowly,without problems.<br /><br />DHP

 

[johnson_stx]

Re: engine chokes when carbs open

thanks all for your advise. However, i found out what my problem was. It seems that my type engine (175HP Johnson) has a shift switch that disables spark to cylinders 1,3 and 5 during the shifting process. after disconnecting the black/yellow wire from the switch to the power pack cylinders 1,3 and 5 fire. I can now advance the carb linkage cable and the engine revs up like normal, no more choking and dying. thanks again.