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Old 27-08-2013, 22:46   #1
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Hard starting 3gm30

The 3gm30 in my 1990 C&C 34+ runs great when running, but when cold has a tough time getting going. I have to give it a lot of throttle and 3-4 full seconds of cranking to get it started and then is sputters for a bit with plenty of blue smoke before it settles in. Any ideas as to whats up?

Thanks,

Dave
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Old 27-08-2013, 22:56   #2
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Re: Hard starting 3gm30

First thing I would check is the mixing elbow. The elbow on our 2gmF was almost completely blocked, which made for very difficult starting. The exhaust blockage was just before the water inlet, so the water was still flowing freely out the back of the boat.
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Old 27-08-2013, 23:06   #3
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Re: Hard starting 3gm30

Neo, that is a great idea. You mean the exhaust loop right? The sorta big elbow before heading out to the muffler thingy, yes?
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Old 27-08-2013, 23:09   #4
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Re: Hard starting 3gm30

Mixing elbow or bad injectors most likely.

Is it hard starting hot too?? Any oil usage?? If so it could be rings in one or more cylinders.

Any water in the oil or oil in the water?? That would be a head gasket.
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Old 27-08-2013, 23:56   #5
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Re: Hard starting 3gm30

Sorry, did I say easy. I just pulled up my post from last year. I should have said, "relatively easy".

I have the fresh water cooled 2GM which, along with the 3GM, is notorious for blocked mixing elbows, especially if you run the engine at low rpm.

Here is the link to my post on sail.net, hope it helps.

Yanmar 2GM20F mixing elbow Pearson 31-2 - SailNet Community
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Old 28-08-2013, 02:18   #6
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Re: Hard starting 3gm30

Quote:
Originally Posted by Neo View Post
Sorry, did I say easy. I just pulled up my post from last year. I should have said, "relatively easy".

I have the fresh water cooled 2GM which, along with the 3GM, is notorious for blocked mixing elbows, especially if you run the engine at low rpm.

Here is the link to my post on sail.net, hope it helps.

Yanmar 2GM20F mixing elbow Pearson 31-2 - SailNet Community
IIRC the mixing elbow jointing nipple has right hand and left hand threads.
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Old 28-08-2013, 10:04   #7
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Re: Hard starting 3gm30

No water in the oil, no excessive oil consumption and it starts instantly when warm. It actually runs pretty good "seemingly" except for starting when cold.

Dave M.
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Old 28-08-2013, 11:04   #8
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Re: Hard starting 3gm30

I vote leaky injector then. It only takes one bad injector to make a 3gm hard to start. Oh the discharge ell does need to be looked at now and then too, I ckeck mine once a year or so.
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