Hesitating / Bogging / Warm Engine only
I have a 1988 Tri-Star open bow with the Ford 351 engine, carburetor. It has about 800 hours on it.
I have owned it for about 10 years and have only done any minor repairs (other than a new interior) since owning it. New starter, regularly replaced impeller, regular tune ups by MasterCraft mechanic.
It's been running strong. Starts right up if it's been used within a week or 2. Needs a few cranks of it's been sitting.
My issue occurs only after the boat has been running for about 30 minutes or more. It never happens until it's been running for a while.
Here's the issue:
When the boat is accelerating from idle, like pulling up a rider or a tube, the engine bogs and hesitates. Where it would normally take 3-5 seconds to get up on plane, it takes 5-8 seconds.
It DOES do this when I'm not pulling a rider, but not as bad.
Occasionally while it's hesitating, it seems to cough. Not as loud as a backfire, but louder than a normal stuttering or hesitating.
Again, it only does all this after the engine has been running for about 30 or more minutes.
I recently had a mechanic here to check the fuel filters and it looked good. He did NOT fully remove the carb, but he did check the linkage and mechanics of the carb and said it was all good. He did check the plugs and they seemed good.
He tightened the alternator belt as it was a little loose.
Any other things I can try? I'm not super skilled, but I can do some basic things. I've replaced the raw water pump, starter, belts, etc. I can do some basic electrical, and I can test voltages.
Someone suggested that it might be the accelerator pump on the carb. My guess is that it's time for a full carb rebuild as it's not been done in the 10 years since i've owned the boat. My concern with that is getting it properly tuned once it's back on the boat.
Anyway, this is all I can think to mention. Any help or suggestions would be great.
PS, the boat is in Florida on a private freshwater lake. It's on a lift in my back yard and I don't have the trailer. There is a MasterCraft dealer within 15 miles, but they are expensive.