Found loose Venturi in problematic carburetor

[BatteryMan]

Motor: 1974 model 110 Kiekhaefer 9.8HP Serial # 3486640

Motor was running fine then suddenly stalled out during a high-speed run. Had to keep the carb almost fully choked to keep it running. Took the carb apart, and found the plastic venturi loose inside the throat of the carb. I can't figure out how the venturi was originally attached inside the carb. I tried operating the outboard with the venturi removed, but the motor does not run unless 80% choked. I pulled the high speed nozzle out of the carb to see how the venturi and nozzle parts might have originally fit together, but the hole in the venturi fits loosely on the tip of the nozzle (maybe this is why it fell off in the first place). I have a replacement venturi on order hoping that a new one will fit more tightly. I think I can tell the orientation the venturi should have inside the carb throat.

My questions are:

1) how do you mount a replacement venturi?
2) does the venturi stay on with friction alone, or is loctite or some other adhesive required to keep it on the nozzle?


Thank you.

 

[racerone]

There is a hole in the venturi ( bottom ) and the nozzle screws into it to hold it in place. No glue required.

 

[BatteryMan]

I don't see any threads on the tip of the nozzle that is exposed inside the throat of the carb. I will send pictures of what I'm looking at later. Do you have links for any diagrams or write-ups that I can reference?

 

[racerone]

No pictures neede for me !--------I have replaced those boost venturi's before.-----------The nozzle screws into the carburetor body and sticks into the venturi to hold it in place.--Elegantly simple , no glue required at all.

 

[BatteryMan]

Awesome clarity. Thank you for the response. I'm hoping that replacing the venturi restores engine performance. Does it make sense to you that the carburetor doesn't function properly without this little plactic piece in the air stream? I'm used to Evinrude/Johnson style carbs that draw fuel through the open neck of the nozzle without extra airflow enhanced by venturi attachments.

 

[racerone]

It is a " boost venturi "----------------Put it back in and it will run properly again.-----------------If pieces were broken off then where are they ?------------Seen pieces of them stuck in reed valves.

 

[BatteryMan]

One of the little wings on the venturi is missing, so I'll pull the manifold and check the reed valves. I'm glad you mentioned that!

 

[racerone]

If you see it you might be able to pull it out ( got a wee dental mirror ) -----------There is no intake manifold to remove , the reeds are internal.

 

[BatteryMan]

Worked like a charm! Thank you!

 

[Joeee]

Does anyone have a picture of where and how the Venturi fits in on 9.8 Mercury 1982

 

[racerone]

Do you see the hole in the venturi ?----The nozzle fits into that hole when you screw the nozzle in place.----That holds it.----Fairly simple I think.