Tapping noise

[donschweika]

Have a '96 4.3/V6 mercruiser. Runs real good, but there is a tapping noise when accelerating sometimes. Could it be the timing? If it is what should the timing be? Where can I find an owners manual or service manual? Sorry for all of the questions, but I am rather new to power boats.

Thanks in advance for any help.

By the way the boat will cruise all day at 3200 RPM.

 

[Fishermark]

Re: Tapping noise

there is a tapping noise when accelerating sometimes.

Hard to tell exactly what that is of course without hearing it... BUT - it sounds like you are describing pre-ignition. (More of a rattling sound as opposed to tapping though).

IF is it pre-ignition, you need to be careful as that can damage your engine. Check you timing and you may need to go up an octane in fuel.