Yanmar 3GM30F Starting Problems

[Tom Payne]

Hey engine mechanics. I need some advice with a problem I am having on my 3GM30F. 50% of the time I have a hard time starting my engine. It feels like it is either flooded or not getting any gas. I push the button and the engine just spins and will not start until I slowly push the throttle to full. Then when I hear the engine starting to catch I let off the throttle and watch all this white smoke come out my exhaust. Once I run the engine for the day or awhile, it will always start right up. But if I wait a week, I have the same problem at my inital start up. One more question???I read in the yanmar manual, you should let your engine idel for 5 to 10 minutes, then, in neutral, rev your engine to 32 - 36 rpm's before shutting her down. I talked to a mechanic at a marina, he said he has never heard of reving the engine before shutting her down. Some how I think this problem could be related, maybe, maybe not.I have experimented shutting her down with the rev up and with out, I still have the problem 50% of the time.All your help and advice is greatly appreciated.Daddy's Dream

 

[Pete]

check fuel pump check valve

there was/is a service notice about a bad check valve on the later model 3gm engines. Check at Torrison marine web site or here in the archives. The problem you are having sounds like what was happing with the notice where the engine was bleading down the fuel creating a hard to start engine Hope this helps!

 

[Bob]

Bleed the system

Try beeding the system. First at the fuel filter and then at each injector. If there is any air in diesel fuel the engine will be hard starting. Also, is your fuel fresh?Good luck!

 

[Sam Lust]

A few thoughts for you

Depending on the vintage of your engine yours may be subject to a problem with a fuel line and check valve on the engine. As I recall the steel line from the lift pump, and the check valve it connects to on the injection pump are removed and replaced with a braided steel covered flex line. Apparently the set up allowed air to seep into the system from the fuel tank return line.Another thing you will want to do is to basically re-plumb the fuel hoses from the tank to the engine. It is likely you are getting air into the system from bad connections. Very often the leakage is too slow to be noticed during the day or over the weekend, but over a weeks time it can leak in enough air to make starting tough. If you have any evidence of fuel on the outside of your fuel lines they are questionable.Last item: check the engine stop cable where the outer housing bottoms in a boss at the engine. It's possible the housing is not firmly fixed in place and is being pushed back when you shut the engine down. Then, when you try to start the engine the stop valve is in the shut off position. (Please don't ask me how I know about that last one!)