Boat is a 98 Regal with twin 5lt, 2bl (GM with Mercarbs),
I have had ongoing running problems with a boat I purchased end of season last year. I have dealt with water in fuel, carb overhaul, ignition timing, new spark plugs and confirmed firing order and still running poorly. I though it was a bad carb as but switched with the other motor and still terrible. I have switched modules as well to test, all external parts seem to be original.
Compression is good from 148-155psi.
The motor was apparently overhauled due to overheating a year before I purchased the boat and did not get used a whole lot.
Basically the motor runs poorly at idle, (sounds kind of like it is trying catch up to itself like late timing) which makes me think 4 cylinders are running well. Midrange it sounds like it is blubbering as if fuel was dribbling into one venturi, the engine does seem pretty good above 3,500rpm. The engine vibrates in Neutral and in gear and definitely is much louder than the good running engine.
After switching carbs and realizing that was not it I'm thinking there is something related to a camshaft failure, incorrect camshaft timing or incorrect part.
The boat is gone into storage for the winter and unfortunately I did not check with a vacuum gauge while I had access. I am wondering if the valve covers can be removed without pulling exhaust manifolds and can the intake and camshaft be replaced with the boat in the water?
Also is it common for camshaft to fail in marine applications?
Thanks for your help.
I have had ongoing running problems with a boat I purchased end of season last year. I have dealt with water in fuel, carb overhaul, ignition timing, new spark plugs and confirmed firing order and still running poorly. I though it was a bad carb as but switched with the other motor and still terrible. I have switched modules as well to test, all external parts seem to be original.
Compression is good from 148-155psi.
The motor was apparently overhauled due to overheating a year before I purchased the boat and did not get used a whole lot.
Basically the motor runs poorly at idle, (sounds kind of like it is trying catch up to itself like late timing) which makes me think 4 cylinders are running well. Midrange it sounds like it is blubbering as if fuel was dribbling into one venturi, the engine does seem pretty good above 3,500rpm. The engine vibrates in Neutral and in gear and definitely is much louder than the good running engine.
After switching carbs and realizing that was not it I'm thinking there is something related to a camshaft failure, incorrect camshaft timing or incorrect part.
The boat is gone into storage for the winter and unfortunately I did not check with a vacuum gauge while I had access. I am wondering if the valve covers can be removed without pulling exhaust manifolds and can the intake and camshaft be replaced with the boat in the water?
Also is it common for camshaft to fail in marine applications?
Thanks for your help.
