I have a Yanmar YSB 12 in a 1977 Catalina 30 that struggles to start. The odd thing is that when it does start, it appears to run fine. After it is warmed up and I shut it down, it will start right back up immediately. If I wait as little as 10 minutes it will struggle to start again. I've owned the boat for 6 years and this has been a new issue. The starter died last season and the new starter appears to turn the motor over slower than the old one. Any ideas? Should I release the compression before I turn the engine over?
Yanmar YSB 12 Hard to Start
- Thread starter Doug Tilford
- Start date
I have a Yanmar YSM12. (No better engine anywhere.) It will start if it is getting fuel and will turn over. Sounds like you might have a fuel pump problem. If intake is handy, try very small shot of starter fluid or choking with your hand.
Start with all the connections from the battery to the starter and make sure they are clean, tight, and free of corrosion. Next check the battery condition. How old is the battery? Does it still hold a full charge?
A very small air leak between the lift pump and the tank can let the fuel syphon back to the tank a little leaving a small air bubble that requires some cranking to get fuel back up and the engine running.. Suspect the banjo fittings and any clamped fitting or the hose itself if it is old..
Welcome to the group, Doug !
Welcome to the group, Doug !
Doug, the YS series diesels can be a little cranky. A tiny shot of starter fluid in the intake always works. Better yet, check the setting on the fuel injector pump. There is a small punched dot on the adjuster screw. Try various settings of the screw until you find something that works. On mine, the dot is towards the bow. 6 o'clocking down on it. Of course the system has to be free of any air.
The sole is done and I moved on to other projects
Complete rewriting engine to control panel including gauges, sensors... only thing origional is buzzer and glowplug relay. Just wrapping up plumbing engine hot water to hotwater tank. That expanded to new hoses on engine, relocate raw water strainer, new raw water pump, up size hoses.
Les
Complete rewriting engine to control panel including gauges, sensors... only thing origional is buzzer and glowplug relay. Just wrapping up plumbing engine hot water to hotwater tank. That expanded to new hoses on engine, relocate raw water strainer, new raw water pump, up size hoses.
Les
Hi Doug
I have been a long time lurker here, but as your problem is familiar to me I decided to jump in.
My engine is a 38 year old YSE 12.
I would suggest that your problem can be solved by resetting the linkages as suggested by Seanshine.
The manual is a little confusing so I will add my amended version plus a pic.
My engine ran out of fuel a few years ago and wouldn't start well, so I tried everything until I finally came across a comment on this blog.
http://www.angelfire.com/rnb/malcsworld/boat/YanmarYSengines.html
He suggests resetting the linkages at intervals. I did that and it fires up first shot every time.
I still don' know why resetting fixed it!
Set the throttle to full power/open.
Loosen the connecting screw lock nut. (1)
Turn the connecting screw (2) until the punch mark is in the 12 o'clock position when looking down on it.
Only the connecting screw pin and no thread should protrude though the governor arm..
Loosen the regulator spindle lock nut (5) and lock bolt (6).
Lightly screw in the regulator spindle (4) until it seats.
Tighten the lock bolt (6) and lock nut (5)
Turn the connecting screw (2) counter clock-wise until the punch mark is in the 9 o'clock position when looking down on it.
Tighten the lock nut (1).
Add a small amount of grease to the connecting screw pin.
With fingers push lightly against mechanism. It should move freely against the spring pressure.
Start her up.
The Yanmar YS is noisy. It vibrates BUT it is the toughest little engine on the block.
I did a 200 mile trip down the east coast of Japan against wind and current all the way.
The yammy never missed a beat.
Best of luck and let us know how it works out
Gary
I have been a long time lurker here, but as your problem is familiar to me I decided to jump in.
My engine is a 38 year old YSE 12.
I would suggest that your problem can be solved by resetting the linkages as suggested by Seanshine.
The manual is a little confusing so I will add my amended version plus a pic.
My engine ran out of fuel a few years ago and wouldn't start well, so I tried everything until I finally came across a comment on this blog.
http://www.angelfire.com/rnb/malcsworld/boat/YanmarYSengines.html
He suggests resetting the linkages at intervals. I did that and it fires up first shot every time.
I still don' know why resetting fixed it!
Set the throttle to full power/open.
Loosen the connecting screw lock nut. (1)
Turn the connecting screw (2) until the punch mark is in the 12 o'clock position when looking down on it.
Only the connecting screw pin and no thread should protrude though the governor arm..
Loosen the regulator spindle lock nut (5) and lock bolt (6).
Lightly screw in the regulator spindle (4) until it seats.
Tighten the lock bolt (6) and lock nut (5)
Turn the connecting screw (2) counter clock-wise until the punch mark is in the 9 o'clock position when looking down on it.
Tighten the lock nut (1).
Add a small amount of grease to the connecting screw pin.
With fingers push lightly against mechanism. It should move freely against the spring pressure.
Start her up.
The Yanmar YS is noisy. It vibrates BUT it is the toughest little engine on the block.
I did a 200 mile trip down the east coast of Japan against wind and current all the way.
The yammy never missed a beat.
Best of luck and let us know how it works out
Gary
Attachments
Starter fluid a definite NO unless it is a dire emergency, and the compression release, yes. Does your engine have glo-plugs or a preheat before start? If so, and it isn't working, that would make it hard to start. This could be coupled with the slow starter (low voltage?). Air in the fuel lines and poorly adjusted linkages as mentioned above are also posibilities. Lastly, it could be timing. It's the last thing I'd check and it might require a competent marine mechanic to help you here.
Good luck.
Good luck.
You can look up the history if you are interested but basically, the original Yanmar small single horizontal cylinder diesel motor from around 1970 was the YSE 8/12 series (nominal 8hp & 12hp), around 1975 that series was replaced by the YSB-8/12 series and around 1979 by the YSM-8/12 series. These are basically all the same motors and may parts are interchangeable. They do not have any preheat or glow plugs but are a very simple and reliable motor that just keeps on going and going and going and...... The YSM-8/12 series was replaced by the single vertical cylinder GM-10, etc. series.
My CAL 2-25 sailboat has the original 1979 YSM-12 and I also had my original starter die a couple of years ago. I got a cheap US$100 + shipping clone universal (verses a Yanmar brand) starter from an ebay store but it ran notably slower and was not reliable starting unless I used an electric hair drier or a butane torch to preheat the engine block and the incoming air and a very small shot of WD-40 spray (never use a car motor starter spray on a diesel). I complained to the ebay store and they shipped my another starter at no cost and they did not want the original returned. It also ran notably slower with the same starting problems.
After a consulting some sailing friends, I took the original starter with the burnt solenoid contacts and worn out carbon brushes to a local auto-electric shop and had it rebuilt for about CDN$150. problem solved!!!!!!!!
Bottom line for reliability, get rid of the new cheap slow speed starter and rebuild the original one.
Remember to always place the regulator to 50% or higher position for starting and you may need to use the decompression leaver for a couple of seconds to get the motor to speed before starting.
My CAL 2-25 sailboat has the original 1979 YSM-12 and I also had my original starter die a couple of years ago. I got a cheap US$100 + shipping clone universal (verses a Yanmar brand) starter from an ebay store but it ran notably slower and was not reliable starting unless I used an electric hair drier or a butane torch to preheat the engine block and the incoming air and a very small shot of WD-40 spray (never use a car motor starter spray on a diesel). I complained to the ebay store and they shipped my another starter at no cost and they did not want the original returned. It also ran notably slower with the same starting problems.
After a consulting some sailing friends, I took the original starter with the burnt solenoid contacts and worn out carbon brushes to a local auto-electric shop and had it rebuilt for about CDN$150. problem solved!!!!!!!!
Bottom line for reliability, get rid of the new cheap slow speed starter and rebuild the original one.
Remember to always place the regulator to 50% or higher position for starting and you may need to use the decompression leaver for a couple of seconds to get the motor to speed before starting.
You folks are awesome! I'll be down at the boat this weekend and will take your advice. I'll let you know if I can get her started right!
Doug,
I have another suggestion, if it is that the engine turns over slow, where there isn’t enough voltage at the starter to to wire length or connection loss. I did a modification of my Yanmar 2GM20F and added a relay, look at this post for the mods:
https://forums.sailboatowners.com/i...ng-harness-issue.186160/&highlight=SirMichael
Mike
I have another suggestion, if it is that the engine turns over slow, where there isn’t enough voltage at the starter to to wire length or connection loss. I did a modification of my Yanmar 2GM20F and added a relay, look at this post for the mods:
https://forums.sailboatowners.com/i...ng-harness-issue.186160/&highlight=SirMichael
Mike
The cheep D&R ebay starter just turned too slowly to get enough compression to start combustion on my single cylinder YSM-12 without a bit of help from an electric hair dryer or a small shot of WD-40. As I said above, the best and most cost effective solution is to get you original Yanmar starter rebuilt. Don't listen to people who don't know this simple single horizontal cylinder motor.
Hi Gary, Thanks for your help on adjusting the governor. Unfortunately, it did not help me get the motor started. I'm mostly convinced its the aftermarket starter I purchased. It turns the motor over really slow. I've checked voltage at the starter and I'm getting a good 10-12 volts when turning the engine over. I'm told this is good. Anyone have any other ideas? I can get an OEM starter from SEI Marine (not gear reduction) . What do you folks think?
I just reread you original post, Doug.
I got the wrong message and didn't realize that the "struggle to start" was turn over speed.
I though it was turning, but not catching. Sorry to send you down the wrong track.
Anyway, if the starter won't turn it ,the good thing is that it shows you have good compression. LOL.
Did you try using the decompression lever to get a bit of speed up?
Gary
I got the wrong message and didn't realize that the "struggle to start" was turn over speed.
I though it was turning, but not catching. Sorry to send you down the wrong track.
Anyway, if the starter won't turn it ,the good thing is that it shows you have good compression. LOL.
Did you try using the decompression lever to get a bit of speed up?
Gary
thanks Gary, your post saved me lots of anguish. i got air in the fuel lines while replacing the filters, i thought i got it all out, but didnt. i got the motor running again after properly bleeding the lines, but it wasnt coming up to full power, was throwing all kinds of white smoke and wasn't starting as easily as it used to. i reset the governor linkage after reading your post and poof all problems were gone. thanks for taking the time to post this!
Hi Chris.
That was my first post. 5 years ago.
I am very pleased that it helped you out.
One more little Yanmar YSE tip.
The (pump) regulator spindle has an o-ring.
This probably the only part that is vulnerable to deterioration.
If you ever pull the pump apart or have trouble starting, replace that o-ring.
If you can't get a Yanmar part, take the spindle and old o-ring into a good parts shop and lay them on the counter.
That is what I did. 20 cents for two!!
gary
That was my first post. 5 years ago.
I am very pleased that it helped you out.
One more little Yanmar YSE tip.
The (pump) regulator spindle has an o-ring.
This probably the only part that is vulnerable to deterioration.
If you ever pull the pump apart or have trouble starting, replace that o-ring.
If you can't get a Yanmar part, take the spindle and old o-ring into a good parts shop and lay them on the counter.
That is what I did. 20 cents for two!!
gary
