I recently re-powered my rig with twin 1999 Yammi 250 ox66 EFI's. Splashed them in the water for the 1st time yesterday. While motoring out in no wake zone (4 mph), Starboard engine sounded temp alarm after about only 5-10 minutes. I shut it down and continued out w/ port motor. Ran the boat for 10 minutes at various rpm's w/ port motor only-smooth as silk. Dropped the Starboard motor back down after temp had cooled and ran both at low RPM's for 15 minutes-no alarm. Gradually increased rpm's, still no temp alarm, but noticed Starboard engine was running a bit rough. When rpm's increased, it had a persistent, steady cough as though running on 5 cylinders. Running on only the starboard engine, this was more noticably and the boat labored a bit to get up on plane w/ just starboard motor (port motor popped the boat up on plane easily). All I was equipped to do was some visual inspection as I ran out of time. Plugs, coils secured, all esle seemed normal. I also installed new water pressure gauges. Port motor ran normal pressure (10-15 under way, almost 0 at idle) but starboard motor would only tach the gauge up to 3 or 4 psi or less while at 3500-4000 rpms.
What are the likley culprits? Any relation to low water pressure and this type of behavior?
Thanks
P.S. I'll also mention that during the installation the Starboard motor fell from a height of about 18". Impact was limited to negative terminal on starter, lower cowl and 1 spark plug. All plugs were replaced along w/ plug coil wire that was damaged. Plug coil wire was taken from 1994 Yammi 225 I replaced-they looked like the same parts.
What are the likley culprits? Any relation to low water pressure and this type of behavior?
Thanks
P.S. I'll also mention that during the installation the Starboard motor fell from a height of about 18". Impact was limited to negative terminal on starter, lower cowl and 1 spark plug. All plugs were replaced along w/ plug coil wire that was damaged. Plug coil wire was taken from 1994 Yammi 225 I replaced-they looked like the same parts.