Hi i'm hoping someone has a suggestion cause Im about stumped. I have a 30
foot sloop with a 20 hp 1989 Perkins Perano inboard diesel motor. Up until
now I have done many hundreds of hours with impeccable reliability.
Recently the motor wasnt used for 2 months as I was doing some work on the
bilge that required the removal of the exhaust system. When I next took it
for a run I noticed the following problem.

Problem: Then engine starts fine runs smoothly accellerates normally up to
max revs (3000) rpms in neutral. Previously it would run up to 3000 rpms in
forward or reverse, even with a dirty prop the engine would quickly
accellerate to full revs, even tied at the marina or in open water.
Currently when the engine is put in gear on the mooring it will only do
2600rpm ahead and 1800 rpms in reverse.

The revs climb normally until it reaches eg 2600 in forward then the
throttle keeps moving for the rest of its travel until up against the full
revs stop but the engine wont rev any higher. Its the same in reverse but
it wont go above 1800rpms.

The more load the engine is put under the less revs it can attain at max, ie
if motoring through the water forward and 5knots and I give it a blast of
reverse, prior to the problem it would thrash away at 3000 revs in reverse
now it will only do about 1500rpm against the extra drag of sliding through
the water forward. The engine uses very little oil and there is no visible
smoke from the exhaust.

So far I have tried: - checking the throttle to make sure it is travelling
through its full range on the motor - it is.
- I have stripped and inspected the entire fuel feed system from motor to
tanks, all hoses are clear, fuel runs freely at every point, I have replaced
all fuel filters and cleaned water trap, all was spotless.
- to test fuel pump pressure I put engine in reverse applied max throttle,
it went up the 1800rpm. I then cracked the bleed valve on top of injector
housing to see if it was starving of fuel, it did not suck air but squirted
out excess fuel, indicating more than sufficient fuel being supplied by pump
at engine.
- The exhaust system had been checked and a few hoses replaced when I was
working on the bilge recently so it should all be ok, I did check the mixing
elbow where the salt water enters the exhaust and this was coked up so I
replaced that but the problem remains.
- I have checked the air intake but it is clean and clear and I tried
running it with the engine hatch open just to make sure enough air was
getting to the motor but no difference.
- I also dove under the yacht and checked the prop, a little dirty but
nothing that should affect it much.

I am about stumped, other than normal servicing no other work has been done
to the motor which might cause this, I havent played with the injectors or
pump settings etc. I am open to any suggestions.



regards


Steve Hopkinson

"Rachel and Steve" wrote in message
...
snipped
I am about stumped, other than normal servicing no other work has been
done
to the motor which might cause this, I havent played with the injectors or
pump settings etc. I am open to any suggestions.


regards

Steve Hopkinson
===========

There was a discussion about something similar (though not exactly the same)
in Practical Boat Owner no 446 February this year in "Ask The Experts" on
page 69. I don't entirely understand your problem and I similarly don't
entirely understand the article but there are enough points of similarity to
lead me to point to it. The heading was "Yanmar engine revs"

Hoges in WA
Remove the zeds.

There was a discussion about something similar (though not exactly the
same)
in Practical Boat Owner no 446 February this year in "Ask The Experts" on
page 69. I don't entirely understand your problem and I similarly don't
entirely understand the article but there are enough points of similarity
to
lead me to point to it. The heading was "Yanmar engine revs"

Hoges in WA
Remove the zeds.

Thanks Hoges but I can't seem to access the Ask the experts column online
from PBO's website. I will try and find that copy next time I am in the
library.



regards


Steve Hopkinson

Ask 'em nicely if they'll email it to you? It's not that big.

--
Hoges in WA
Remove the zeds.


"Rachel and Steve" wrote in message
...

There was a discussion about something similar (though not exactly the
same)
in Practical Boat Owner no 446 February this year in "Ask The Experts"
on
page 69. I don't entirely understand your problem and I similarly don't
entirely understand the article but there are enough points of
similarity
to
lead me to point to it. The heading was "Yanmar engine revs"

Hoges in WA
Remove the zeds.

Thanks Hoges but I can't seem to access the Ask the experts column online
from PBO's website. I will try and find that copy next time I am in the
library.



regards


Steve Hopkinson