3gm30 runs wide open

[Scott T-Bird]

I think crosswind had it right originally. Make sure the fuel control rack is lined up so that the pin fits in the fork of the governor arm shown in the attached diagram (labelled Governor Level 2). I had my injector pump off a few years ago and the manual stressed that the pin needs to fit in that fork or you could have an engine that doesn't shut off. Perhaps the pin is seized as you suggest. If I remember correctly, there is a plate on the timing gear cover just under the injector pump that you can remove to peer inside and verify that the fuel control rack is aligned properly. Once it is fit properly, I don't know how it is possible for it to slip out, so I'd bet there is something else that is a factor, but I'll suggest that the alignment of the fuel control rack is the crux of your problem. There should clearly be a pin that fits in the fork so that the governor arm slides the rack back and forth. If the rack is open and it's not sliding, the engine will run at wide open. The maintenance manual explains it pretty well as I recall. I'm not a mechanic but I was able to remove & reinstall the timing gear case cover and fuel injection pump without much difficultly. What I'm writing could be based on faulty memory, I'm sure. It was a 1-1/2 years ago.

Yanmar 3GM30 - No Fuel at Injectors 2 and 3 - Cruisers & Sailing Forums

Hi to all from NZ, I have posted in another thread but I think this subject deserves its own heading for those in the same situ later. My motor has been sitting for 7yrs whilst we rebuild our boat .(&a

www.cruisersforum.com

Scroll down in the link to find the diagram.

 

[NCBrew]

Have to say i have some experience here having rebuilt my fuel injector pump (stupidly I might add), but after reassembling it a few times to get it right discovered an interesting phenomenon with the yanmar injector pumps.

There is a small pin that goes through the housing keeping the cylinder chamber in its proper place and it can back out allowing the timing between the cylinder and the chamber to be out. The result of this is exactly what you are describing. The engine will run full RPM with no control from shut off or throttle.

The good news is it is a very easy fix. Simply push the pin back in and use your own special method to prevent it from backing out again. (***** punch/adhesive/whatever).

The bad news is you have to remove the injector pump and disassemble it to get the pin in place. It's tricky but with the service manual and a good acumen, it can be done.

Reach out to me if you need the manual as I have it in PDF. format. Also we can talk it through verbally if you chose to go this route.

IMHO as always.

CW

 

[NCBrew]

Have to say i have some experience here having rebuilt my fuel injector pump (stupidly I might add), but after reassembling it a few times to get it right discovered an interesting phenomenon with the yanmar injector pumps.

There is a small pin that goes through the housing keeping the cylinder chamber in its proper place and it can back out allowing the timing between the cylinder and the chamber to be out. The result of this is exactly what you are describing. The engine will run full RPM with no control from shut off or throttle.

The good news is it is a very easy fix. Simply push the pin back in and use your own special method to prevent it from backing out again. (***** punch/adhesive/whatever).

The bad news is you have to remove the injector pump and disassemble it to get the pin in place. It's tricky but with the service manual and a good acumen, it can be done.

Reach out to me if you need the manual as I have it in PDF. format. Also we can talk it through verbally if you chose to go this route.

IMHO as always.

CW

Can you send me the PDF of the manual. I am Patrick Ponsonby (NCbrew)
Please send the manual to dadinnc@gmail.com