Vacuum ports clogged on 90hp power head (pics)

[fire7882]

I'm in the process of pulling apart 2 power heads and both of them have clogged vacuum ports on the bypass covers. Each power head has one on the port and starboard sides. What is the purpose of these ports and why are they so small, allowing them to become easily clogged?

 

[fire7882]

Re: Vacuum ports clogged on 90hp power head (pics)

Forgot to mention both motors are crossflow. One is a 1988 and the other a 1992.

 

[Cofe]

Re: Vacuum ports clogged on 90hp power head (pics)

Not for sure, but could those ports be check valves? What is the model number of you're engine?

 

[fire7882]

Re: Vacuum ports clogged on 90hp power head (pics)

Thanks, I haven't thought about it being a check valve. I'll check this afternoon. One is a E90TLEND(1992) and the other is E90TLCCA(1988).

 

[fire7882]

Re: Vacuum ports clogged on 90hp power head (pics)

They don't allow flow either way. I cleaned one out with a small wire and there is no evidense of any check valve. Anyone know their purpose and what whould happen if they became clogged? If they are used to help regulate fuel flow, then wouldn't the motor run lean if they were clogged causing heat and lubrication issues?

 

[emdsapmgr]

Re: Vacuum ports clogged on 90hp power head (pics)

These ports are part of the late model recirculation (fuel) system. It is not shown well in the parts catalogs. This system is designed to draw off excess fuel that may accumulate behind the reed cages and feed it direct into the combustion process. Functioning properly, the engine should idle better. The ones on the bypass covers should be open and clear. The valve on the other end of that hose is a one-way valve. The factory service manual has a section on this system, including a hose routing diagram.

 

[fire7882]

Re: Vacuum ports clogged on 90hp power head (pics)

Thanks for all the info. I found the section in the service manual and cleaned out all the ports with a small needle.