www.iFourWinns.com

After about 15 hours I have developed a significant engine knock at 800-1200 rpm after warm up, goes away above that. I am using a Lucas fuel additive and it was broken in properly. Also sometimes has a little dieseling if I shut it down too quickly. Could be timing issue? Any thoughts would be appreciated.

New boat? quit talking to us and warranty it.

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1981 Columbia 8.7
2015 Yamaha FZR - 87mph - sold
2006 Yamaha GP1300R - sold
2003 Chaparral 215 SSI - sold
2009 Stingray 195CS - sold
2000 Four Winns H180 - sold
1976 O'day Daysailer II - sold
Rick's Four Winns H180 Mods/Upgrade Thread

I'm assuming your talking the kinda knocking from the fuel system, NOT the kind of knocking that comes from a bad main bearing? I second ric (but you can keep talking to us ) Definately, if it is a new boat, call your dealer.

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

Dieseling problem is low octane fuel. In Oz I have to run 95 or 98 Octane. Regular unleaded as provided by marinas is not enough and the engine diesels on every time. Fill with 98 and its perfect.

Ric had a good idea previously and that was to go up one jet size in the carb - still to try this.

"Significant knock" is not a good sign at all. Sounds like a serious manufacturing defect at 15 hours.

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Alec

2006 Horizon 190
VP 4.3GL/SX, Sunsport