Dave,
This link below should bring up the service manual for the M20, on p. 17
of the .pdf, Fig. 37 shows the HP pump with the governor on the left
end. It's kind of integral to the pump, looks difficult to remove
separate from the pump. If sticking is the issue one thought would be
to try to flush some diesel oil, maybe with some Marvel Mystery Oil
added, in through governor while it's in place. You'd have to open up
the top of the unit, which gets tricky pretty fast, but if you could
just get a gap you could flush oil through. You could hold the
compression release down and spin the engine while spraying. After that
I'd flush with lube oil and do an oil change.
As I mentioned I took one of these apart last year, contact me off line
if you want to talk more about it.
https://www.google.com/search?q=universal+westerbeke+M20+governor&client=firefox-b-1-d&biw=1017&bih=651&ei=FBY4YeOmLe2l5NoP0Zq34AI&oq=universal+westerbeke+M20+governor&gs_lcp=Cgdnd3Mtd2l6EAMyBQghEKABOgcIABBHELADOgoIABBHELADEMkDOgUIIRCrAjoHCCEQChCgAUoFCDwSATFKBAhBGAFQnt0YWObtGGCj7xhoAXAAeACAAawBiAGOCJIBAzQuNZgBAKABAcgBCMABAQ&sclient=gws-wiz&ved=0ahUKEwjjgLj3oO7yAhXtElkFHVHNDSwQ4dUDCA0&uact=5
Neil Gallagher
Weatherly, 35-1
Glen Cove, NY
On 9/7/2021 10:36 PM, Dave via CnC-List wrote:
Thanks Neil – We did check for fuel returning but only at varying
no-load RPMs, not under load.
There should be no air or water in the system- we also ran it from a
jury rigged tank, no filter, clean fuel, so I’m pretty sure those
basics were eliminated.
No offense taken – most of the time people do miss these things.
We haven’t torn things down too far yet. Any way to check for a
sticking governor?
Dave
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows
*From: *Neil Gallagher via CnC-List <mailto:[email protected]>
*Sent: *September 7, 2021 10:13 PM
*To: *Dave via CnC-List <mailto:[email protected]>
*Cc: *Neil Gallagher <mailto:[email protected]>
*Subject: *Stus-List Re: universal M20 diesel question
Dave,
Sure sounds like a fuel issue. The governor does not restrict flow,
it sets the rotation of the plungers in the HP pump which controls how
much fuel in delivered to the injectors. The fuel not used or which
leaks by the pump plungers is what returns to the tank. Under light
load you'll hardly see any return fuel, more as the load goes up.
The governor works by a balance between a spring and flyweights, the
throttle lever adjusts the spring tension and engine speed sets the
flyweight position. A quick look at the M20 tech manual shows the
governor is right in the HP pump assembly, it's possible the governor
is sticking and causing slow response but it may also be worn fuel
pump. You'd have to pull the whole assembly and send for rebuild. Cost
me about $700 for that on an M3-20B engine last year on my club launch.
Before that extreme, however, let me ask the more obvious questions
(don't mean to offend, just asking): any water in the fuel? That
could give a slow response, or maybe an air leak on the fuel supply
hoses, though it sounds like you've checked that?
Neil Gallagher
Weatherly 35-1
Glen Cove, NY
On 9/7/2021 9:16 PM, Dave via CnC-List wrote:
Evening all. Trying to help a neighbour here with a diesel
issue. His engine will rev freely at idle but with the
transmission engaged in either forward or reverse, revs increase
very slowly and only to 1800-2000 RPM on the tach. (whether
tach is accurate or not, RPM under load is much lower than
no-load, and RPM increases quite slowly.)
We have verified that neither the exhaust system nor the fuel
supply to the high pressure pump is obstructed. Air Intake is
clear. The speed lever works smoothly to its full travel. The
compression release is not engaged. The engine runs a new facet
electric fuel pump with plenty of flow.
When the engine is running, no fuel returns to the tank via the
return line. The return line is not blocked, at least not
downstream from the return barb at the injector. I am not sure
under what circumstances the fuel should return to the tank in a
diesel, as the return occurs after the high pressure pump.
All This leads me to suspect a fuel (volume) problem but i am not
exactly sure where to look next. I believe all that’s left
are injectors and high pressure pump. The high pressure pump has
a governor, not sure if that functions by restricting fuel flow.
Any thoughts?
Many thanks! Dave 33-2
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send contribution -- https://www.paypal.me/stumurray Thanks - Stu
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costs involved. If you want to show your support to the list - use PayPal to
send contribution -- https://www.paypal.me/stumurray Thanks - Stu
