Exhaust Restriction in 3.0 L Merc ??

[jimmmy]

I just bought a 1989 Oliver 1650 with a 3.0L I/O Mercruiser. The carb was removed and rebuilt last month prior to buying the boat. Can't get more than 3000RPM and tends to bog when given full throttle, although will rev to 4500 out of gear. New mechanic took off carb and said it was full of water again and flooding. Re-rebuilt and re-installed. Same symptoms!! He now thinks there might be some kind of restriction in the exhaust?? Another Mercruiser mechanic told me he had a similar problem that 5 carb re-builds would not cure. The carb was pitted from water and the cure was a new carb. Presto worked fine. Anyone experienced similar problems?

 

[dhammann]

Re: Exhaust Restriction in 3.0 L Merc ??

classic symptons of water in the fuel. Also there was a service bulletin for that year for incorrect float height...float level was too high causing flooding at idle due to the inherent vibration of a 4 cylinder. The gasket above the float bowl also needed to be modified by cutting excess gasket material out of the way so it would not interfere with the float travel.

 

[jimmmy]

Re: Exhaust Restriction in 3.0 L Merc ??

Mechanic says carb fine now, but he believes there is an exhaust restriction?? He says there is supposed to be a flapper valve in the exhaust that is not there and he thinks it has fallen down into the exhaust somewhere, causing restriction. He's starting to pull the engine to get at it. Sound reasonable???

 

[denniz]

Re: Exhaust Restriction in 3.0 L Merc ??

If a shutter breaks it could hang in the exhaust see it all the time, But Ive NEVER had to pull a engine to get it out. Id pull the drive, and see if you can get it out thru the exhaust bellows.