Prop is clean....shouldn't matter if the prop is dirty, the engine won't
rev above 2,100 RPM's when in neutral.
On 2022-06-27 12:32 p.m., Korbey Hunt wrote:
Is the prop clean?
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*From:* Robert Abbott via CnC-List <cnc-list@cnc-list.com>
*Sent:* Monday, June 27, 2022 5:58:50 AM
*To:* Josh <muckl...@gmail.com>; Stus-List <cnc-list@cnc-list.com>
*Cc:* Robert Abbott <robertabb...@eastlink.ca>
*Subject:* Stus-List Yanmar 2 GMF
Josh:
Revived the engine at the slip out of gear (neutral)....same result,
tack goes up to +2,100 RPM's .....providing more throttle does not
increase the RPM's. Pretty sure the tack is working just from the
sound of the engine and maximum hull speed it could attain (maybe 4 knots)
Yes, getting black smoke especially just after starting the engine and
reviving it a bit....then it stops.
Boat can not motor up to hull speed right now at 2,100 RPM's.
All good tips and very helpful however I am leaving it in the hands of
the marine mechanic. I asked him to address this problem and give the
engine a thorough inspection. He said he would get to it
today.....fingers crossed.
Rob
On 2022-06-26 11:50 p.m., Josh wrote:
You should also try to rev the engine with it out of gear. If it has
the same problem of reaching full RPM then fuel and air delivery are
nearly to only possible culprits.
A bad or weak governor spring would be indicated by an engine that
has a tendency to over speed or hunt. Pulling the throttle faster
applies pressure to open the fuel rack and provide more fuel. More
fuel create more RPM and the governor the creates a feedback force
that resists the fuel rack. The governor tries to slow the engine
whereas the throttle tries to speed it up. Without the governor the
engine will tend to race, have high RPM, limited throttle control,
and is lively to overspreed.
When you get to 2100 RPM do you get heave black smoke? If you do the
engine is getting plenty of fuel but not enough air. Have you
checked or simply removed the air cleaner? When was the last time
the backlash was checked on the lifters. I can walk you through it
if you don't know.
If you're not getting black smoke, are you getting any change in smoke?
Are you getting a correlating loss of power or stumbling? Or is it
just not going faster? Was it not able to push the boat at normal
full speed. Are you confident in the accuracy of the RPM gage. You
can get a laser tach from Amazon for less than $20 to confirm the RPM.
As the high pressure fuel pump and fuel injectors age they have
springs that get weak. Weak pump springs will allow the tappets to
"float" and not achieve a full intake stroke of fuel....causing a low
fuel condition resulting in lower RPM. If the injectors are dirty or
have weak springs they won't achieve full fuel pressure before
injection and may even leak a small amount into the cylinder before
TDC. This is probably good more likely to cause detonation (ping or
knock), not exacly low RPM but none the less is sub optimum operation.
Have you checked the oil for fuel dilution? The fuel lift pump is
driven off a cam and if the diaphragm cracks or tears it will leak
fuel into the crank case. This may also let crankcase pressure into
the high pressure fuel pump...reducing fuel delivery and RPM. Pull
the dip stick, drop some oil on a paper towel. Smell it for diesel
smell. Wait and observe for a halo. Especially if you have red
diesel the halo is seen as the clearish red halo around the black oil
spot.
If all of that checks. Then you need to get a little more invasive.
A compression check is in order. I can walk you through it and
provide parts(tools). It is definitely doable as DIY but you got
some investigation to do first. Let me know. Reach out with a PM and
we can talk.
Josh Muckley
S/V Sea Hawk
1989 C&C 37+
Solomons, MD
Jun 26, 2022 09:39:09 Robert Abbott via CnC-List
<cnc-list@cnc-list.com> <mailto:cnc-list@cnc-list.com>:
Went to take the boat out Friday for a short sail .....motoring
out heading into a12 knt breeze....started to increase the RPM's
and found the engine wouldn't rev about 2,100 RPM's ....marine
diesel's are not supposed to be that complicated but they are to
me. I wouldn't know where to start to trouble shoot....getting a
mechanic to deal with it this week. I spoke to him and told him
the situation and he thinks it is a fuel problem....engine not
getting enough fuel....my fuel tank and fuel should be clean as I
had the bottom of it replaced 2 years ago and the 2 fuel filters
replaced. He thinks one or both of the filters are restricting
the fuel flow.....I hope he is right but I don't think so.
Possibly many are causes....restricted fuel injectors, fuel pump,
etc. ....the engine has never been serviced in the 16 years I
have had the boat
Any insight or guidance to help greatly appreciated.
Rob Abbott
AZURA
C&C 32 - #277
Halifax, N.S.
