My 548 came off the dyno running great, but we ran it with his fresh air system. In the boat it is now loading up very bad at idle. My guess is that the Livorsi 9in flame arrestor is choking it out. Has anyone else had this problem? Thanks.

I'd be suprised if any flame arrestor could choke it out at idle. More likely, I would check float levels - the engine is probably in a different angle than the dyno, and it may be flowiing over the nozzles. Look down the carb throats at idle.

Just talked to my marina buddy and he said the same thing. I will check that. Thanks for the heads up.

Floats is a good place to start. Check the level with the boat in the water at the dock.

if the flame arrestor was chocking it out at idle i doubt it would run at all on the top end......

Plus it takes two seconds to remove the flame arrestor to eliminate that as the culprit.