hard to start yanmar

[RayJones]

Has anyone come across this before? A Yanmar 2gm is very hard to start from cold ie after about a week.Once started it starts first time everytime , runs like a dream. New fuel filters, new fuel hoses, injectors serviced, injector pump tested and serviced, spill timing checked and re set.Washers on fuel connectors replaced
o rings in lift pump replaced. I give up!

I think the fuel is draining back thru the fuel lift pump but a new pump costs $250 in Australia and there is no kit available.
Any suggestions.

 

[pete]

same prob on my 1 GM 10 early this season,after a lot of checks including a compresion test it turned out to be a spring linkage between the governor on the crankshaft and the rack on the diesel pump not returning to full fuel for starting (rack fully forward on my engine), I could have put my finger in the oil filler point on front of engine and flicked it off had I known now it starts imediately when cold. good luck

 

[Guest]

You may have to prime the fuel pump if engine has not been used for some time.

 

[RayJones]

Thanks to pete and nutcracker for your replies.
The injector rack is fine, the injector pump has been checked and calibrated.
Yes I do have to prime the pump and bleed the system after each idle period ie two days to a week. I just wondered if any one had come across this need to bleed and what did they do. Thanks again Ray jones Yacht Masquerade.

 

[hugh_nightingale]

Had a similar problem on my Diesel car.
OK if started immediately but after any time really difficult.
Again cured by priming.

Turned out to be just like your own suggestion, fuel draining back.
This caused by a small leak in the system, would you believe in the priming pump?
Just after a major service as well, so it will pay to check all joints for tightness and all seals for soundness. In my case the pump diaphragm had split.

Hugh

 

[Guest]

Ray,

Does bleeding the system sort the starting problem or not? If it does then as others have suggested you probably have a leak if not then I bet it is a compression problem.

I spent a good couple of years putting forward various theories about why a Yanmar 2GM on a university boat I was involved with wouldn't start as you describe. One of the theories was the fuel draining back one, but as priming didn't improve the situation we gave up on it. Did most of the servicing you have mentioned but finally gave up and took the head off and discovered we had slightly bent con rods and therefore a lack of compression.

My suggestion is you get someone to do a compression test for you.

Hope this helps,

Dave

 

[waterrat365]

I have a similar problem. For whatever reason, I discovered that if I shut down the engine (a Yanmar YGM8) with the shutoff cable, it re-starts much easier than it would if I had closed down the throttle, even days later. Also, I discovered that the banjo fittings at each end of the fuel line- there are fittings at fuel lift pump, filter, and fuel injector pump, have a pair of washers made of soft copper. My engine is 21 years old. Any guess on how many times the fuel line has been bled? Hundreds, maybe thousands of times! Each time a copper washer is tightened, it becomes work hardened and less able to compress, and therefore, will leak slightly at each joint in time. The cure is new washers, or, in a pinch, remove the old ones, wash them off, file them smooth, heat them red hot on a stove, then quench them in ice water to soften them up again. When reapplied, they will prevent the slight but persisten air/fuel leaks that occur in time when continued bleeding has been an unwanted feature of cold-starting.