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Old 10-12-2016, 11:43   #16
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Re: Yanmar 3GM30f hard starting

Thanks for all the replies. Will prioritize starting with Sailorchic's list.
Everything , incl tank is new or cleaned/refurbed except for rings/bore/valves.
Will do the sound test with decomp levers first.

What is a dip tube? Dip stick tube?
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Old 10-12-2016, 12:15   #17
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Re: Yanmar 3GM30f hard starting

Dip tube is the tube in the fuel tank that pulls fuel from the bottom. As the engine starts easy when warm, probably not that.

A small vacuum leak in the fuel system can cause the same starting issues as bad rings. Hard to start at first, easy after first time.

BTW yanmar lists moving the throttle forward a bit when first starting. I generally only need this on a cool/ cold day. The GM being a strict compression engine (no glow plugs), well it can be a tad cold blooded first thing on a cool day

If there is no sound difference on the decompression levels and there is no venting of air / smoke from the oil fill hole when running, then compression is good.

IF you do get a venting noice and smoke out the oil fill, then you have excessive blowby. Normally caused by bad / broken rings. With a yanmar GM engine ring wear would not normally fall outside new tolorances with 1100 hours on it. So a low hour engine with bad compression would need R&R ing.

If you do have bad rings, you can read about how to rebuild a yanmar gm here with my summer of discontent, back in 2013: http://www.cruisersforum.com/forums/...ar-107705.html
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Old 10-12-2016, 12:26   #18
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Re: Yanmar 3GM30f hard starting

I think its the filter, had the same problem , I removed the filter everything was fine. also had that problem with a 83 ford diesel, i bypassed that filter, no problems. I dont think its internal, worn out diesels still run.
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Old 10-12-2016, 12:48   #19
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Re: Yanmar 3GM30f hard starting

1. Try this, I found the link I mentioned earlier:

Many many previous posts on this subject. Try this one, includes a neat solenoid solution used by many skippers:

http://forums.sailboatowners.com/index.php?threads/replacing-engine-starter-switch-on-a-h31.178401/&highlight=yanmar solenoid solution

I really wish one of you with a Yanmar would make this answer a sticky

2. Don't use the hand primer on the Racor. I tried that once years ago and my finger still hurts! Install an electric fuel pump.
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Old 10-12-2016, 13:53   #20
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Re: Yanmar 3GM30f hard starting

Quote:
Originally Posted by lateral View Post
Thanks for all the replies. Will prioritize starting with Sailorchic's list.
Everything , incl tank is new or cleaned/refurbed except for rings/bore/valves.
Will do the sound test with decomp levers first.

What is a dip tube? Dip stick tube?
Sailorchics post is very good. Just like to say we have very low compression ( worn out bore) & need near full throttle to start when cold but will start easily the rest of the day. I think its related to lubricating oil being on the cylinder wall to help with compression. What we do now is spin up the engine when cold with the decompression lever engaged until some oil gets splashed around & then let it go & it starts straight away but ours is a single banger Yanmar. so I dont know if you can do that on yr 3 cylinder. I found nylon washers much easier to seal on the banjo bolts than copper washers & would check fuel leaks first with those low hours
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Old 10-12-2016, 14:06   #21
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Re: Yanmar 3GM30f hard starting

Quote:
Originally Posted by Stu Jackson View Post
1. Try this, I found the link I mentioned earlier:

Many many previous posts on this subject. Try this one, includes a neat solenoid solution used by many skippers:

http://forums.sailboatowners.com/index.php?threads/replacing-engine-starter-switch-on-a-h31.178401/&highlight=yanmar solenoid solution

I really wish one of you with a Yanmar would make this answer a sticky

2. Don't use the hand primer on the Racor. I tried that once years ago and my finger still hurts! Install an electric fuel pump.
Sorry if I wasn't clear. No problem with cranking. Starter motor works fine every time. Just doesn't want to run. If you don't keep starter turning over it will slowly die.
I have search ad infinitum but needed a short list.
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