Yanmar GM10 engine problem.

[fishtank1]

Hello
Please help. Have 12 year old Yanmar GM10 engine that has had minimal use. At the end of last season noticed a lack of top end speed. This season it ran a low tick over for about 15 seconds before stopping could restart with same result. renewed filters, fuel, checked lift pump operation had injector pump and injector professionally tested to no avail. Manipulated the govener control on injector pump rack through oil fill hole and was able to keep the engine running. Does anyone have any experience of removing the front engine cover which contains the governer mechanism and are there any pit falls. Or any other ideas what this problem is?

 

[bendyone]

Check the exhaust elbow for a build up of carbon.

 

[Slinky Spring]

Yes I have done this job recently. First challenge was to get the pulley wheel off. Big nut was very tight and took some shifting. After that I had to wedge the pulley and tap the end of the shaft before the wheel came off. Remember to put nut back on loosely so as not to damage the threads when hitting it. Then removed all the bolts and the injection pump and the cover came off simply.
Governor mechanism is mounted inside the cover. The spring that is often the cause of problems is mounted on the shaft of the mechanism. To replace it you need to remove the end of the mechanism which involves driving out a pin. This proved a bit of a challenge. It will only come out one way as the pin has a slight head on it at one end. You will need to grip the mechanism in the vice to do it.
When you put it all back together make sure it is loose and moving freely. Mine was not and i had to take it all apart again.
Before doing anything i would speak to the guys at marine power. They are very helpful and will give free advice.
PM me if you have any other questions.