'Ello gov(ernor)!

[zephyr070]

It's crazy to think I only bought my used (and to some extent, abused) '89 Vision 32 only two years ago. I am a chemist by trade, and love all things engineering, so I was eager to start correcting the mistakes of the six previous owners - and boy have I been busy! I was able to update the critical systems, starting with electrical, to a status worthy of an extended cruise through the San Juan Islands last August, which was probably one of the greatest payoffs to hard work I've ever experienced.

I decided I would address one major project per year, as time and funds allowed, and this year that task was to get my Yanmar 3GM30F in "more reliable" condition, namely to address the very common hard starting issues. Injectors professionally rebuilt (I tried, but it was beyond my skill to heal), fuel injection pump green-lighted by the same, highly reputable shop, head rebuilt, valves lapped, valve stem seals replaced, new hoses, new fuel piping and seals, new lift pump...and she still wants to die at idle. I have finally arrived at the big Boss fight: it is time to inspect the governor. I am hoping and praying a certain sailorchic34 might be listening in here, as I know her experience from lurking around this excellent forum before.

The issue: Hard starts have been an issue since I bought the boat, with the exception that after motoring for the day, hitherto, she started right up even after sitting dormant overnight. Since having all that work done, the engine wants to turn over within a couple seconds of cranking, which is wonderful. Even with some blow-by, the compression is adequate that she wants to kick off right away, and does...but does not sustain operation for more than a couple seconds unless I really push the throttle up. I find a happy spot where she should be idling, around 750-850 rpm, and set the idle adjustment screw to that position. She's happy for a couple minutes then wants to climb waaaay up in revs once she realizes where that regulator lever is really set! This makes me think something is temporarily binding, or the governor springs are worn to the point where they don't properly balance out the centrifugal force of the governor flyweights anymore.

I had a good think about this and approached as logically as I could. "What does this behavior resemble?" Answer: it's as if I'm pulling the engine stop lever, aka denying the engine adequate fuel for sustained combustion (no, it's not a stuck cam in the fuel cutoff mechanism). "What would mimic that behavior?" A couple possibilities, one of which is air getting into the low pressure end of the fuel system, which would have a greater effect at low revs than high, where a larger volume of fuel is being delivered.

Here's the deal: it's not air in the fuel. I know this to be a 100% certainty. "But maybe you didn't tighten that one bleed screw enough?" It is *not* air in the lines, trust me. Every single millimeter of the fuel delivery system has been exquisitely inspected, repaired, replaced, etc. Fuel comes blasting out of every bleed point with zero air bubbles before being tightened back down.

All this to say: Does anyone have a feel for governor work in this model engine? Any tips would be helpful before I take that timing gear cover off.

Cheers all, and fair winds!
-Kevin

[Adelie]

Sailorchic34 bowed out 14mo ago.
Sorry

[zephyr070]

Originally Posted by Adelie

Sailorchic34 bowed out 14mo ago.
Sorry

That's too bad! I was really hoping to pick her brain since she's been all over every square inch of a 3gm30. Hopefully someone else will be able to offer to some insight. In the meantime, I think I'd better get some parts quotes together.

[chris mac]

I'm far from being a mechanic. But I have 2 of the 3gm30's.
I had similar problems, hard starting, especially cold, and rough idle that went away when I changed out the exhaust system.

Maybe just the elbow, or old hose, but worth looking at.
Good luck

[zephyr070]

Originally Posted by chris mac

I'm far from being a mechanic. But I have 2 of the 3gm30's.
I had similar problems, hard starting, especially cold, and rough idle that went away when I changed out the exhaust system.

Maybe just the elbow, or old hose, but worth looking at.
Good luck

Thanks! Brand new stainless steel mixing elbow and union (I will never, ever buy Yanmar's POS cast iron elbow again), and reworked exhaust line/waterlock muffler. Like I said, it kicks like a mule when starting now, but will not sustain power.

2 3gm30's - are you on a cat, or is one a spare for parts?

[JPA Cate]

Our member "Wotname" is a pretty savvy engine guy.

Ann

[chris mac]

Originally Posted by zephyr070

Thanks! Brand new stainless steel mixing elbow and union (I will never, ever buy Yanmar's POS cast iron elbow again), and reworked exhaust line/waterlock muffler. Like I said, it kicks like a mule when starting now, but will not sustain power.



2 3gm30's - are you on a cat, or is one a spare for parts?

On a cat. 1993 and still purring.
That's about the extent of my available knowledge, good luck.
I'm interested to hear the cause and fix

[Westcliffe01]

Perhaps try a modern multigrade oil ? There are 10W40s out there now and even 5W40 and it makes an incredible difference to cold operation. You seem to be based in higher lattitudes ? Higher oil consumption could be one side effect in a worn engine that has historically been run on regular straight grade oil.

[Jamme]

For a moment I thought you were discussing about a certain NY state politician 🤪

[djousset]

I am a sailor chic, but not THAT sailor chic. But I've been chasing air through my 2gm20f for much of this season and trying to learn about the governor and idle, so I'll be tuning in. As Ann said, Wotname knows a lot. He, among others offered me excellent advice.

[Wotname]

Crikey, no pressure guys...

Disclaimer - I am not a professional mechanic, just simply have pulled apart a few small Yanmars, owned a coupled, had to solve too many problems caused by (others) neglect and have too much time on my hands. I do know (mostly) what questions to ask though .

But most importantly, I haven't had to resolve any gov issues on a Yanmar GM series engines so I can't help much.

I'm not sure of the exact nature of the problem. You say it starts OK when cold but doesn't hold an idle rpm, is this in neutral or when in gear?
Does it idle OK when at normal operating temperature (in neutral and in gear)?

Does it work OK at higher rpm in neutral?
Does it work OK at higher rpm under load (i.e in gear)?

Does any of the above change when the engine is at normal operating temperature?

Assuming it starts OK when stone cold and simply doesn't want to idle even when hot, then the problem must be lack of fuel or possibly timing.

Have you confirmed the timing?

Lack of fuel can only be air, injector pump or governor.

I presume you have the service manual; if not, there is one in the CF library or I can email you one.

Hopefully the real mechanics will tune in soon - SkipperP, JimB, DougR et al.

If not, we will muddle along somehow

[zephyr070]

Originally Posted by Westcliffe01

Perhaps try a modern multigrade oil ? There are 10W40s out there now and even 5W40 and it makes an incredible difference to cold operation. You seem to be based in higher lattitudes ? Higher oil consumption could be one side effect in a worn engine that has historically been run on regular straight grade oil.

I am indeed running a multi grade oil, and neither burning any, nor “making any” (no diesel in the sump)! The issue persists even when the engine has been run at cruising rpm for several hours. Fuel delivery is at the core of the problem.

[skipperpete]

Here’s a couple of suggestions that might help eliminate some of the possibilities.
Sticky fuel rack:
The stop lever directly controls the injector pump fuel rack control lever in one direction only via a cam on the stop lever and to establish if the rack is sticky, operate the stop lever rack from the run position to the stop position and feel the resistance and contact with the rack control lever. There should be a slight click and a little resistance as the rack moves to no fuel and the same “feel “ should exist for repeated operations of the lever. The rack control lever should follow the stop cam back to full fuel position repeatedly.
My next suggestion was air in the system but you already have that pretty well covered but as a last ditch attempt to eliminate that possibility, get a container of fuel and some clear plastic fuel line and gravity feed fuel directly into the injector pump from the tank in the cockpit.
Be prepared to do an emergency shutdown by closing off the air intake (and the breather pipe to the rocker cover) while you’re experimenting with a potentially sticky injector pump.
Pete.

[zephyr070]

Originally Posted by skipperpete

Here’s a couple of suggestions that might help eliminate some of the possibilities.
Sticky fuel rack:
The stop lever directly controls the injector pump fuel rack control lever in one direction only via a cam on the stop lever and to establish if the rack is sticky, operate the stop lever rack from the run position to the stop position and feel the resistance and contact with the rack control lever. There should be a slight click and a little resistance as the rack moves to no fuel and the same “feel “ should exist for repeated operations of the lever. The rack control lever should follow the stop cam back to full fuel position repeatedly.
My next suggestion was air in the system but you already have that pretty well covered but as a last ditch attempt to eliminate that possibility, get a container of fuel and some clear plastic fuel line and gravity feed fuel directly into the injector pump from the tank in the cockpit.
Be prepared to do an emergency shutdown by closing off the air intake (and the breather pipe to the rocker cover) while you’re experimenting with a potentially sticky injector pump.
Pete.

The injection pump came back from the shop with a perfect bill of health - the fuel rack slides back and forth like butter. I did operate the stop lever while the pump was out and I could actually see the mechanism in action. The cam/control "fork" (what the manual calls governor lever 2) appeared to function properly through several cycles, however, since I am fixin' to remove inspect the whole governor train anyway, I will take another look at the cam when I can get both hands on it!

[zephyr070]

Originally Posted by Wotname

Crikey, no pressure guys...

Disclaimer - I am not a professional mechanic, just simply have pulled apart a few small Yanmars, owned a coupled, had to solve too many problems caused by (others) neglect and have too much time on my hands. I do know (mostly) what questions to ask though .

But most importantly, I haven't had to resolve any gov issues on a Yanmar GM series engines so I can't help much.

I'm not sure of the exact nature of the problem. You say it starts OK when cold but doesn't hold an idle rpm, is this in neutral or when in gear?
Does it idle OK when at normal operating temperature (in neutral and in gear)?

Does it work OK at higher rpm in neutral?
Does it work OK at higher rpm under load (i.e in gear)?

Does any of the above change when the engine is at normal operating temperature?

Assuming it starts OK when stone cold and simply doesn't want to idle even when hot, then the problem must be lack of fuel or possibly timing.

Have you confirmed the timing?

Lack of fuel can only be air, injector pump or governor.

I presume you have the service manual; if not, there is one in the CF library or I can email you one.

Hopefully the real mechanics will tune in soon - SkipperP, JimB, DougR et al.

If not, we will muddle along somehow

Lots of great questions! I'll try to answer them in order:

-It does start when cold, but won't hold idle rpm, unless the idle adjustment screw is advanced pretty significantly, then it hums at 750-850 in neutral...until it realizes how far the idle position has been adjusted and slowly climbs to that fuel delivery level as "something" comes unstuck/starts working properly. Incrementally backing off the idle adjustment screw has the predicted effect: rpm drop down monotonically with each turn of the screw, until about 1050 rpm, then the fuel starvation behavior takes over and the engine stalls out slowly over a few seconds.

-Yes.
-And yes.

-I ran the engine for several hours at cruising speed, and still saw this issue after shutdown/sailing/restart. Luckily it didn't screw with me while coming into the dock.

-I'm not sure how I would confirm the timing, however, I can say that the exact same shims that got me through 10 days of uneventful cruising last August are still in there. For the timing to suddenly go out would require a serious and sudden complication with the camshaft, no?

-I do indeed have a copy of the service manual! I can draw a lot of things from memory now...which is maybe not such a great thing :/

Thanks for the suggestions, so far. We muddle forward!