Missing top of throttle

[captcrunch]

1988 38c with 485hp 671 tib's. Boat will not go above about 2250rpm at wot both 26th the glendennig engage or both throttles at the pins, feels like there it's no further pull on the cables at the end of the throttle range, any ideas what to look at

 

[Boatsb]

How clean is the bottom and the props?

A little sludge on the hull can do that.

 

[captcrunch]

They're clean. I wish it was that simple

 

[Boatsb]

Fuel or air restrictions ?

Dirty hull and or props?

Anything beyond those are kind of rare. They don't go out of tune on their own that quickly.

 

[captcrunch]

How would I check fuel or air restrictions fuel filters are New

 

[Boatsb]

Vacuum gauges

How are the turbos?

How clean is the air induction and cooling components ?

 

[captcrunch]

I think they are all clean, I may have to look through this again with my mechanic then

 

[MikeP]

As noted, barnacles/other junk on the props/running gear will cause the problem. With a load of barnacles...our boat will not exceed around 1800 RPM and max speed of 11 knots or so! Clean the props/shafts - normal RPM and top speed! Doesn't take much.

Will the engines achieve full no-load RPM in neutral sitting at the dock? (checked individually, no synchronizer involved). If it will, check for full no load RPM with both engines running/synchronizer engaged. Note that if individual engine RPM is not set properly per Glendinning instructions, the Synchro may disengage at max RPM..or at idle RPM.

Did this problem suddenly occur? IOW, were they achieving proper RPM the last time out and now won't?

Was any work done on any related components between the time that they worked OK and now?

 

[davidwigler]

New air filters? What kind?

 

[motoryacht lover]

I had a similiar issue that was intermittent on one engine. I have Hynautic controls and it ended up being this Hynautic part called a bungee. My point is maybe look at the controls and cables, etc.