Occasional backfire?

[Tclark]

Just had a re man 5.0 efi put in boat from my marina. I believe they did a great job getting in and sounds and runs smooth. At least I think. Taking boat home by water from marina was about 1.5 hr trip by water. I am following all the proper break in procedures for varying rpms. After about an hr drive I heard what was backfire 3 times. Not all at exact same, maybe during a 1 min span approx 3500 rpms. Put boat in neutral and open cover, to see if I could pin point backfire after getting back to speed. Never had a another back fire for the remaining 30 min drive....Any ideas as to what it could be? No rpm fluctuations, engine sounds so smooth...

 

[fastjeff]

Might be water in the gas.

Jeff