Zero Throttle Response

[AEROCOOK]

I just put my new (to me) boat with a 1988 merc 60 hp in the water and discovered that there is a problem. I started it up and let it warm up for a minute then when I put it in forward and gave it throttle, nothing happened. It was as if the motor wouldnt rev beyond idle, there was no studdering or rough running in fact the idle was excellent, but it just would not go. I checked the throttle cable and it's working as it should. The boat has not been run in 2 years, so I suspect carbs are the fault??? Any ideas?

 

[Plainsman]

Re: Zero Throttle Response

Do the RPM's increase? Is it going into gear?

 

[AEROCOOK]

Re: Zero Throttle Response

Do the RPM's increase? Is it going into gear?

Yes it is going into gear. no the RPM's do not increase, I dont have a tach, but I estimate less than 1000 rpm.
I have the carbs off at this point and the float boals look clean, but according to an earlier post, they can look very clean but still have blocked orifices, so I intend to rebuild or at least clean them. Is there an after market kit I can buy? Merc dealer wants $110.00 for each kit!

 

[Windykid]

Re: Zero Throttle Response

With the cowl off when you go to WOT do the butterfly's open?

 

[Silvertip]

Re: Zero Throttle Response

The throttle cable does not connect directly to the carbs on an outboard. Instead, it connects through a series of bellcranks, cams, and linkage rods so the timing advance plate and throttles work in unison. You probably do not have a carb problem. What you have is missing or disconnected linkage. Obviously the throttle plates are not opening nor is the timing advance moving. Either one connected would make the engine rev.

 

[AEROCOOK]

Re: Zero Throttle Response

The throttle cable does not connect directly to the carbs on an outboard. Instead, it connects through a series of bellcranks, cams, and linkage rods so the timing advance plate and throttles work in unison. You probably do not have a carb problem. What you have is missing or disconnected linkage. Obviously the throttle plates are not opening nor is the timing advance moving. Either one connected would make the engine rev.

I didnt think to check the butterflies and the carbs have been removed at this point, also the motor is at the lake 250 kms away so I cant check till the weekend. The butterfly movement is accomplished by the rotation of a plate, so it should be easy to tell if the linkage is intact even without reinstalling the carbs right?
I have another question about carb cleaning or rebuilding... Is it generally sufficient to clean the carbs (submerged for a few days then blown out with compressed air) or is "Rebuilding" recomended on a motor that hasnt run in 2 years? There are several expansion plugs on the carbs and my concern is what may lerk beneath them?

 

[Chris1956]

Re: Zero Throttle Response

Aerocook, usually you can clean all the carb passageways by soaking and blowing them out. You may need new gaskets, and maybe new inlet needles and seats (if they leak). I would start with new gasket sets and proceed from there.

 

[AEROCOOK]

Re: Zero Throttle Response

Aerocook, usually you can clean all the carb passageways by soaking and blowing them out. You may need new gaskets, and maybe new inlet needles and seats (if they leak). I would start with new gasket sets and proceed from there.

Thank you, thats the first good news today.

 

[Silvertip]

Re: Zero Throttle Response

Reassembling a carburetor with old parts is an absolute waste of time. A rebuild kit is not a major expense and includes a new inlet needle and seat. It does not include the float which generally is not needed and hence not included. When assembling the carb, tip it upside down and gently blow into the fuel inlet fitting. If air passes through you have it assembled wrong or the float is adjusted wrong. If it seals, your good to continue buttoning up the carb. Idle speed and idle mixture adjustments MUST be made with the engine in the water, and not on muffs.

 

[AEROCOOK]

Re: Zero Throttle Response

Thanks to all who responded to my post.
The motor is running perfectly now, just soaked the carbs for 2 days and blew them out as suggested, no new parts as nothing was worn or damaged including gaskets.
Now onto "Project # 2" ... my newly aquired 1974 Starcraft 19 foot aluminum bowrider with 140 hp Mercruiser I.O.
Wife not happy but too cheap to pass up, talk to you in the Mercruiser forum and thank you again.