I had a similar problem on a Yanmar a few years ago. It was indeed the fuel injection system not the exhaust elbow. It might also be caused by build up on the prop so you could check that too.
The membership association for owners of Dufour Yachts
The membership association for owners of Dufour Yachts
I had a similar problem on a Yanmar a few years ago. It was indeed the fuel injection system not the exhaust elbow. It might also be caused by build up on the prop so you could check that too.