3GM30FC Yanmar stops ,when drop RPM

[YARGESOL]

My port 3GM30 runs great. Start easy and run many hours.But,comming to the port and dropping rpm from 2500 to 1000,or so it may stop.Not always. Oil is OK,temperature OK,water is going through.Last season,just after the change of fuel filters (internal and external) were same simptoms,but the water pump belt was slack and worn.I worked out the cooling and exhaust - changed the pump puley,polished the shaft puley,changed the mixing elbow...cleaned exchanger. I will come to my base port soon and will call the mechano.But,appreciate CF advise. If I'm sailing and start the motor just 1/2 before entering to the marina - no problem. So, if motoring,I used to stop port for 1 hour to calm it down and run on starboard. Than start the port for maniobras.

[Wotname]

First up I would remove and clean the exhaust mixing elbow.

[YARGESOL]

I mentioned:installed new SS mixing elbow

[Wotname]

Originally Posted by YARGESOL

I mentioned:installed new SS mixing elbow

Ahh... I misunderstood the information you presented in the OP. I took it to mean the new SS mixing elbow was fitted last season rather than now.

Sorry I can't be more helpful than suggest it might be a linkage or adjustment problem with the throttle arm on the governor or stop lever / cable.

When you do sort it out, can you please post what the problem was as that helps all of us who use CF as a troubleshooting source.

[YARGESOL]

Originally Posted by Wotname

Ahh... I misunderstood the information you presented in the OP. I took it to mean the new SS mixing elbow was fitted last season rather than now.

Sorry I can't be more helpful than suggest it might be a linkage or adjustment problem with the throttle arm on the governor or stop lever / cable.

When you do sort it out, can you please post what the problem was as that helps all of us who use CF as a troubleshooting source.

I will check/adjust the throttle lever and,defenitly will report when the problem will be solved.Thanks for advise

[wannacat]

Had the same problem with my 2GM20F for 3 years. Finally checked the compression and it was low. Rebuilt the motor and it's been great ever since and now I have way more power and speed! Good luck with it!

[DeborahLee]

Check to see if you anti siphon is sufficient. Mine would not want to start after being heeled over to starboard for a long time. Water would back fill through exhaust.

[knot smart]

im not a mechanic, but thats a fuel problem..the higher rpm's and it runs fine and then you push the throttle down and it stalls indicates to me that when you push down theres not enough fuel getting to the cylinder to keep it going.. and the problem started after you changed filters?? somethings up with the fuel supply.. i'd change all filters again first, then pull and clean the injectors..then possibly change the fuel pump last.. but leaning towards blockage in filters or injectors

[YARGESOL]

Yesterday started the motor just before entering the port. RPM less 2000.
Again,mooring to the dock and while switchinng forward/reverse stopped twice.. So, 1-st air leakage and compression. I don't think that water may come through the syphon.But, thanks for advise

[907Juice]

I have a 1gm and had all kinds of problems last summer. I got tired of it all and took all my fuel lines off, blew them out, changed all the filters amd gaskets, and replaced the lift pump. Then put it back together and adjusted the linkage. now it runs like a champ. Can't really offer any suggestions other than do it all again and make sure it is bled correctly. Maybe the second time it'll work the gremlins out.

[ub1]

If you have any copper ferrule fittings they are a prime candidate for leaks and air intake. Replaced all ferrules in fuel system with proper hose fittings. Chased it for a month. 10 minute fix!

[tdoster]

First two items on my list for that problem would be lift pump and worn injectors.

Compression would show up in smoke before idle issue, in my opinion. Exhaust mixer is always a Yanmar suspect on that vintage and should be checked each year, regardless, but you would see lost power at the top end before having idle issues.