Yanmar YSM12 Engine Issues

[amun1000]

Hi - hoping someone can shed some light on the issues we're having with the engine at the moment.

Essentially the engine is having difficulty starting but once going runs fine. If the engine is cold it will take a number of prolonged attempts to get it running. Once warmed up the engine is stopped however any attempt to restart will require 3 -4 attempts using the starter motor. It fires but without the aid of the starter motor it will peter out. Eventually by the 4th attempt the engine will gain enough momentum and start running without the aid of the starter motor. It seems it starts bets with the throttle position at about halfway. I have tried a number of things to identify the issue such as partially blocking of the air inlet (choke) t ohelp force through fuel
I have checked the following things:
Lift pump - with the bleed screw loosened i can see the lift pump is creating pressure
Drained and Cleaned Precipitation tank
Inspected fuel filter.
Turned engine over with bleed screw loosed. There is plenty of fuel being "pushed" through to the cylinder head

There is no sign f any leaks to reduce fuel pressure for this non-glow plug engine

Hoping someone can help because as it stands the engine is unreliable

Thanks any advice greatly appreciated

 

[neil_s]

It is still quite cold out there! My Bukh needs several goes on the starter motor before it will run, this time of year. Perhaps the difference is that once it has started, subsequent re-starts are easy. Maybe your compression is a bit down - it might be worth checking that the valve clearances are Ok.

 

[garymalmgren]

Here is my experience and recommendation.
I ran out of fuel.
After that the engine was hard to start. It cranked over furiously, but took ages to fire up.
I bled the fuel 10 or more times but it didn't help.

Then I read on a General Information site about the YSE
“resetting the governor linkage at very frequent intervals. If the engine dies at low revs, and will not start, ”

I did that and it started immediately and has given no trouble since.
The instructions in the Yanmar manual are a little confusing so I have copied the manual page and re-witten the steps.

let us know if this works.
Gary

 

[amun1000]

Thank you for the replies. I'll certainly check the valves and governor settings. I'l be back up there next weekend and hopefully get a video of the behaviour. I'm also noticing a little bit of oil leakage from the governor pin - suggesting a build up of pressure

 

[Bilgediver]

Thank you for the replies. I'll certainly check the valves and governor settings. I'l be back up there next weekend and hopefully get a video of the behaviour. I'm also noticing a little bit of oil leakage from the governor pin - suggesting a build up of pressure

Firstly DO NOT reduc e the airflow. This is not a petrol engine with a carb but uses direct injection and reducing the air will reduce combustion pressure and make starting more difficult.

The fuel control on this engine is a little bit different. I suspect that the spindle on the engine operates a bypass needle valve. if the valve is shut then there is full delivery and as the engine speeds up the governor opens this valve to regulate the speed.

When I used to tinker with one of these I would confirm the spindle was not only in the right position but was also closed IE it is a threaded spindle and might be 0ne turn or more open. I would undo the clamp on the lever and rotate the spindle carefully till it stopped . Then set up the levers. If your engine is one of these it might be worth checking this.

 

[eebygum]

Hi - hoping someone can shed some light on the issues we're having with the engine at the moment.

Essentially the engine is having difficulty starting but once going runs fine. If the engine is cold it will take a number of prolonged attempts to get it running. Once warmed up the engine is stopped however any attempt to restart will require 3 -4 attempts using the starter motor. It fires but without the aid of the starter motor it will peter out. Eventually by the 4th attempt the engine will gain enough momentum and start running without the aid of the starter motor. It seems it starts bets with the throttle position at about halfway. I have tried a number of things to identify the issue such as partially blocking of the air inlet (choke) t ohelp force through fuel
I have checked the following things:
Lift pump - with the bleed screw loosened i can see the lift pump is creating pressure
Drained and Cleaned Precipitation tank
Inspected fuel filter.
Turned engine over with bleed screw loosed. There is plenty of fuel being "pushed" through to the cylinder head

There is no sign f any leaks to reduce fuel pressure for this non-glow plug engine

Hoping someone can help because as it stands the engine is unreliable

Thanks any advice greatly appreciated

Hi,

My YSE12 had similar starting issues…. It took a lot of electric cranking on both batteries to cold start and it would never electric start once warm, only by hand cranking would it then start. This was a real pain as I was the only person onboard who seemed to have the knack for hand cranking.



I put up with this for two years until I found the instructions garymalmgren provided to reset the Governor and it solved the problem immediately ; I never had to hand crank last season at all.



Definitely try resetting the Governor as a starting point; takes 5 mins and costs nothing.

 

[eebygum]

Here is my experience and recommendation.
I ran out of fuel.
After that the engine was hard to start. It cranked over furiously, but took ages to fire up.
I bled the fuel 10 or more times but it didn't help.

Then I read on a General Information site about the YSE
“resetting the governor linkage at very frequent intervals. If the engine dies at low revs, and will not start, ”

I did that and it started immediately and has given no trouble since.
The instructions in the Yanmar manual are a little confusing so I have copied the manual page and re-witten the steps.

let us know if this works.
Gary

View attachment 132743View attachment 132742

I followed your instructions last season and it resolved my YSE12 starting issues immediately ?

In fact I was trying to find them to reset again, so thanks for reposting.

 

[eebygum]

It is still quite cold out there! My Bukh needs several goes on the starter motor before it will run, this time of year. Perhaps the difference is that once it has started, subsequent re-starts are easy. Maybe your compression is a bit down - it might be worth checking that the valve clearances are Ok.

Cold indeed…. Before I relaunched yesterday I had an electric fan heater warming up the engine compartment and oil sump; worked brilliantly and YSE12 started on first turn.

Once afloat I can do something similar with a flexible diesel heater outlet I have.

 

[garymalmgren]

Wow eebygum.
I am so happy that someone actually believed me enough to try.
You have made my day.
2 beers tonight instead of my usual 1.
thanks.
gary

 

[amun1000]

thank you all for the contributions - I'll be back up at the boat this weekend to execute your recommendations - Cheers

 

[amun1000]

Hi - been up to the boat today and i 've found that i can indeed start the engine again easily , from warm, if i apply pressure to the governor and it moves about 1mm to increase flow. If i dont apply pressure the engine fails to restart. I didnt get the opportunity to try this from cold but will do up on my return next week

So next steps would be adjust the governor so its operating correctly. However i cant seem to make sense from the instructions in the manual - see next post as i cant seem to insert another image on this reply

I've highlighted the part that i cant make sense when relating to the engine

 

[amun1000]

So which bit on the rack needs to align with the reference surface - sorry being a bit dumb here

 

[amun1000]

I've just noticed the marker - is this what they are referring to in the manual - see attached - sorry wont embed image

 

[QBhoy]

Sounds like you may be onto something. But also great to have the oil kept fresh and in good order. This helps with compression as you’ll know. Thinned down oil will drop your compression a fair bit…as you’ll know, these things rely on strong compression to fire.
not sure if anyone has asked…but any indication of smoke when she does fire up ? Blue or otherwise?

 

[amun1000]

There is a small amount of smoke on first fire up but nothing major. Oil has been renewed annually

 

[eebygum]

There is a small amount of smoke on first fire up but nothing major. Oil has been renewed annually

I’ve read on another forum that it’s good to try and warm up the oil sump (in winter/spring) before the first cold start; so the day of launching this season I had my electric fan heater blasting air into the YSE12 engine bay for 30 mins (it was a good way to use up the credit I was leaving behind); brilliant and it started on the first click.

So I’ve invested £9 on a 12V, 100W Silicone Heater Pad for the Engine Block similiar to the one below ; I will keep you posted on how it works

12V 100W Silicone Heater Pad for Engine Block Tanks Oil Pan Heating Plate Mat | eBay