I'm not talking about outboards, but this one has me (and a bunch of other smart folks) totally baffled.

Background: Inboard boat with a Mopar 360 V-8. Has a Flo Scan device that monitors fuel consumption. Going along in rough seas last week, at 2,500 rpms cruise speed, the fuel usage rate increased from 9 gph to 10 as the boat slowed down (from climbing a wave). After the wave passed, however, the rpms came back up to 2,500 and the fuel usage returned to 9 gph. And it did this consistently for hours.

This is a carb motor with the throttle fixed in position at that rpm--it wasn't moving on its own. To me, the fuel consumption should have dropped as the rpms dropped, for less intake strokes per minute were occurring. But it went UP!

Anyone have an explanation?

Jeff