Yanmar 2G Engine Runs very rough under "load"

[Skippie10]

Hi, today, I went out on Lake Michigan and motored around and tried various "approaches" to speed and ramping up to speed. What I found is that if I ramp up to speed slowly, the engine runs smooth. If I try to speed up/turn up the throttle quickly, the engine runs like it is on 1 cylinder (or maybe 2).

So, the vibration is related to fuel feed/fuel burning/acceleration. In other words, it is not a motor mount issue but - rather - a motor/fuel "tuning" issue.

Any ideas?

Don

 

[woodster]

you have yet to say exactly what kind of engine you have ei 2gm..2qm..3gm..ect ect its almost impossible for anyone to troubleshoot a problem with out some good sound info...make..... model....and hours and so on but what you are describing could be fuel delivery related ... it could be injector pump ...air in the fuel lines .....clogged fuel filter .... and even injector nozzle problems

it could also be a clogged fuel pickup tube in the tank ...diesel is notorious for being a breeding ground for all sorts of unwanted growth...start with the pickup tube and work your way forward all the way to the injectors checking for air and leaks as you go ...and now would be a good time to change the fuel filters..... save the expensive stuff for last so you will know that is what you really need

 

[S Maru]

I have a 1986 Pearson with a 2 GM engine that has problems with vibration similar to those noted. Did you find the fix for this problem?

Tom

 

[rich26nc]

Hey Don,
If you decide to engage a mechanic I would like to suggest you call Yanmar HQ in NJ. They maintain a list of mobile factory trained mechanics. Was skeptical about using someone 'mobile' until I was raked over the coals by a marina mechanic that I believe was using my 1 GM as a classroom. Finally got in touch with a landlocked mechanic near Charlotte, NC (I was living North of Winston-Salem at the time). He installed a new cutless bearing and suggested I attach a sacrificial annode. Point is he was an excellent mechanic and very reasonable. I was able to trailer my shoal draft O'Day to his house and that saved a harbor call of between 150 and 200 dollars. But well worth the money to have someone who knows what they are doing. Regards, Rich

 

[Sailm8]

From your description I would check the folding prop again. It seems odd that if you increase power in gear slowly, there is little vibration. Seems like the folding prop is not engaging evenly causing an imbalance. Just my 2 cents worth.

 

[CHARLIE STAGE]

I am curious as to whether the same vibration happens when you are in reverse? That might indicate a propeller problem also. I have never had this problem but I will follow to see the ultimate solution that you find.

 

[S Maru]

It seems that the vibration issue has been corrected. A transmission rebuild did the trick although I am told that there was none of the scoring of the drive cones that are the usual indication of a transmission issue.
There was no known issue in reverse as the vibration tended to occur (when it occurred) from around 1200 to 1800 RPM. I do not go that fast backward!
Thanks for the interest.

Tom