Knock or ping or what?

[durdy]

My 2008 18' Larson has a 4.3l Volvo I/O which has been fully dealer winterized and serviced each year since new.

First time out this year it started fine, idled fine and accelerated a-ok but after about 20 seconds of running at ~2500RPM there were three quick banging sounds from the engine area. Each muted bang was accompanied by a momentary loss of power. I stopped and looked carefully for any loose object that may have been making the sound. Nothing. Started back up and the thing ran like a champ.

It's run super each weekend since, pulling tubes, skiers and boarders with no issues. Two weeks ago the noise and momentary power loss happened again. Very rapid <bang> <bang> <bang> the first time we hit ~2500RPM. Just like the first time it sounded like someone whacking an empty Coke can with a ruler. And again it didn't reoccur.

The boat lives on the lake and is a major pain to take it in to the dealer for a look see. Anything obviously wrong here that requires immediate attention or am I ok living with it this season?

Ideally I'd like to understand what's wrong too...

Thanks.

 

[fossill]

Re: Knock or ping or what?

Check for water in the fuel and filter.

 

[durdy]

Re: Knock or ping or what?

Check for water in the fuel and filter.

Thanks. How do I make this check?

I read about some water sensitive paste and a long stick - is this the right technique for the fuel itself?

How do I tell if there's water in the fuel filter?

 

[Bt Doctur]

Re: Knock or ping or what?

remove the spin on filter and dump in a clear container and look at it. Could be suffering from "fuel phase separation" from the ethanol.

 

[Bondo]

Re: Knock or ping or what?

How do I tell if there's water in the fuel filter?

Ayuh,... Take it off, drain it into a Larger vessel,+ Look...