Loud tapping sound that increases as RPM's do...motor surges

[Reed 'America' Kellough]

2002 Yamaha 200HP VMAX 3.1L

The engine has been regularly serviced with no major problems but the last time the boat was out there seemed to be a tapping noise coming from the motor. As the boat accelerated the tapping would also become faster and louder. Once out of idle there is a long pause before the motor gets power, almost as if you are reving an engine in a car and then let go of the brake. At a certain point the motor seems to grip and then it will take off, before then its slow.

I am unsure what the issue is or if I provided enough information but i would much appreciate some help on what the problem may be. Thanks in advance!

 

[racerone]

This does not sound good.-----------My suggestion is to start with a compression test , if you must , borrow or rent a tester.-------------It may show the condition off the engine.------This test would assentially cost nothing !

 

[justintime]

Sounds like the 02 sensor plug is carboned up

 

[francisleo4]

this does not sound good.-----------my suggestion is to start with a compression test , if you must , borrow or rent a tester.-------------it may show the condition off the engine.------this test would assentially cost nothing !

sound not good....agree with you...racerone

 

[aliboy]

Does the tapping 'go away' once you get 1000rpm or so? Some of that era Yamaha's had issues with weak 'wrist pins' and once they wear you get a distinctive tapping noise at lower rpm's. Shouldn't cause your surge problem however. You can check the wrist pins by removing the plugs, putting a wooden dowel down the plug hole of a cylinder and winding that cylinder to just past TDC. Once past TDC give the dowel a firm push and see if the piston moves down in the cylinder at all. Pretty much if you can detect any movement, the wrist pin is worn. If you get quite noticeable movement, then this is probably your tapping noise.