Yamaha ME421STI

[philaustin]

I have a 8.2 metre Rib with a Yamaha ME421 STi inboard fitted. When the boat is loaded thee is a very significant "turbo" lag before the boat will plane. The engine can take five minutes to hit around 1900 RPM at which time the turbo kicks in and the boat takes off. Anyone had similar experiences?
I also need to obtain a service manual for same engine, any ideas?
Phil

[biffer]

Sounds a heavy boat What revs do you get once it's going

sent from a remote device

[Alan Priddy]

Common problem, adjust the turbo boost screw underneath the pump Alan P

[AMac]

Also heard of problems with the turbo veins getting coated in soot/ oil residue and needing cleaned regular to let the turbo spin up quicker

[Neville]

Phil,

There is also a pneumatic baffle (gate) which blocks off the turbo pressure when too high. This can stick slightly. You will find it (and the actuator) between the inlet manifold and the turbo. You can easily check that it is functioning ok visually and also by moving it with your finger to ensure it is fully open.

Good luck.

[philaustin]

This is fantastic feedback, I am a new member and this is all great advice. The boat revs at around 3800 RMP which returns around 43 knots unloaded and 38 with four divers and twin sets.

[Declanor]

I have a manual if you can find a at of copying it! Can find any online

[kubcat]

Originally Posted by Declanor

I have a manual if you can find a at of copying it! Can find any online

I have been looking everywhere for a manual and can't find one online. If I was closer I would come around and photocopy it myself.

[biffer]

Originally Posted by philaustin

This is fantastic feedback, I am a new member and this is all great advice. The boat revs at around 3800 RMP which returns around 43 knots unloaded and 38 with four divers and twin sets.

thats right on the button then, assuming it's always done it i'd have a look at Al's pump adjustment, i'm not sure the wastegate would bother the speed pickup but it would make the inlet manifold run hot, had that stick on the cummins engine we run

[Roger Marr]

If its the rib I think it is you have a lovely boat, I know the guy who had it built.