Story and back story. About a year ago I replaced my tank vent and
lift pump on my
Yanmar 3GM30F in sailboat. Afterwards I chased an air leak that made me have bleed system every time I started the
motor. I have a factory installed
electric pump that I can turn on to assist with bleeding. It was inconvenient but easy to do. I just turned on the
pump and bleed at banjo bolt inlet to HP injection pump.
Motor would the start right up and run fine for hours. After 8 hours shutdown I would need to bleed again. Always had some
diesel on the pad under the motor and figure it was from a combination or the small leak and my bleeding. About a month ago I got/paid a
Yanmar mechanic to help me trace down the air leak. He was great and we found the leak was due to a wrong size hose/fitting combo mismatch. He changed a fitting on the
Racor and put proper size hose from
Racor to
lift pump. Motor ran great, started every time, didn’t have to bleed anymore. I did however notice I was still having
diesel on the pads under the motor. Over the last month the amount on pad was increasing. Upon my investigation I saw that the leak was coming from around the top of the HP motor injection pump. Motor was still running great and starting with no bleeding needed. Even though we are not near him, we are actively cruising right now, I call the
mechanic that fixed my air leak. We figured it was the o-rings that had become brittle and were leaking. He said it was not a hard job but suggested that it would be better to hire it out instead of
DIY because to be very careful with springs and cleanliness when opening up the HP injection pump.I got a recommendation and hired someone. Let’s save the I can’t believe this guy story and just say I was not impressed with his cleanliness around the open HP Injection pump or handling of the springs. He got it back together with new orings installed. We also replaced all three
fuel lines between the HP pump and injectors. We got the HP
Injector pump primed. Bleed
fuel all the way to the injectors. Got the motor started. It was running rough at low
RPM. Running fine at higher
RPM. No leaking fuel anymore. Since the orings have been done the motor is now hard to start. Before it would start at idle or 1/4 throttle right after pushing start button. Now it takes 15-30 seconds of cranking to get motor running. Once running it is way more rough and clunky at idle than it was. Above 1200 RPM it runs like it did before. I have run the motor for over an hour a couple of times without any issues while running. It will restart easily right after shutdown. But a few hours after shutdown it takes extended cranking to start again. Any help or ideas would be appreciated. I am thinking perhaps the mechanic got some debris in the open pump and screwed up the pump. Or maybe there was some debris in the new fuel lines that got pushed to the injectors. Could there still be air in HP fuel lines or the pump after hours of running. Is there a way to tell if it is the pump or the injectors?