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Dear Terry & Dena, SV Libby #196.
The advice you have received is all very good. I have had the exact same
issue on Cream Puff. The engine is still in its infancy. It only has 890
hours. However, I developed the problem of not being able to get more then
2000 rpm. We could easily reach 6-7 knots at 2000 rpm but there was nothing
more. We also put out a little black smoke when we tried to push the engine
harder. Here are the things we checked before we solved the problem:
1) Replaced Vetus plastic muffler to ensure we did not have an exhaust
obstruction (did not solve issue - we now have a spare one).
2) Checked fuel flow throughout the system (all was good). We were also
getting a little black smoke when we pushed the engine to go over 2000 rpm.
This is also an indication of sufficient fuel flow.
3) Replaced the prop (we have a spare (if Joel is reading this - the
fact we have a spare prop just made him smile)) - did not solve issue
Prior to replacing the prop, I was convinced this was going to solve our
issue. As you can tell by the other posts in response to your question other
great minds think alike.
Our problem turned out to be the turbo charger. I took off the air filter
and casement to the turbo charge to inspect the fan and shaft. I could see
the turbo charger shaft was not turning. I removed the turbo charger, took
it apart and cleaned it. When I put the serviced unit back on the engine -
I would suggest you ensure your turbo charger is working correctly before
going down the prop route. I wish I had done that first and saved the haul
out fee. I agree with others the prop route is the most likely cause,
however the turbo charger will cause the same symptoms and the magic number
is 2000 rpm. The fact you have already had an issue there before, I would
suggest you make sure it is fixed. You can check the turbo charger using a
listening rod. You will hear it whirl at a very high speed and you are
listening for a continuous sound. Please be careful putting you head this
close to the engine while it is running.
Hope this helps.