than you think. But not even close to 3 GPM. There is a return line for the extra fuel. It is used to cool and lubricate the injection pump. Since it is a brand new engine you should be able to get advice from Beta.

Good choice on engine marinizer. I have a 50 HP BV2203, now 11 years and 3000+ hours old. Only things I have done to it are rebuild the raw water pump, replace the injectors and check valve clearances.