RPM Puzzle

[JGreenx3]

Both port and stbd engines comfortably accelerate up to 4400 rpm or so but after a few moments the stbd engine then drops back its rpms by about 5 to 8 percent of what the port engine is giving. Fuel in both tanks comes from same source and each tank refueled at same time. Initial thoughts were water in stbd tank. Change of filter and injectors does not seem to have resolved (seemed to for a few hours). Has been much rain over the boat last few weeks (although under boat cover). Still sounding like a fuel thing? Any other ideas? Many thanks.

 

[flflatrate]

Fuel pressure maybe? Could be a restriction on that side?

 

[ardeprint]

When was the last time you did a tune up? Ne plugs, cap, rotor, etc... If a while, it may be time.

 

[JGreenx3]

When was the last time you did a tune up? Ne plugs, cap, rotor, etc... If a while, it may be time.

Many thanks all for your thoughts. Looks like it may have been crap building up on the injectors from too many hours idling and not enough good cruising to clean them out. Filter worked fine. Fuel pump tested good too. See what happens after injectors get a good cleaning.