Yanmar 1GM10 engine tuning

[rssmith1965]

How do you tune a simple 1gm10( specifically fuel adjustments on the engine itself. If anyone has experience or knows this motor please let me know and let’s talk. I’ve had two supposed “Yanmar” guys look at it and they turned screws and adjusted screw and now it runs worse. Help!!

bobby from Urbanna

 

[Tally Ho]

How do you tune a simple 1gm10( specifically fuel adjustments on the engine itself. If anyone has experience or knows this motor please let me know and let’s talk. I’ve had two supposed “Yanmar” guys look at it and they turned screws and adjusted screw and now it runs worse. Help!!

bobby from Urbanna

Before you start messing “with screws”, it is a good idea to try understand what is going on. These diesel engines are pretty simple, and need fuel, air and compression to run. No carburetors to deal with. The GM series is very simple.

The basics would include…and it almost always boil down to a fuel issue…

1) Fuel - Is your fuel clean? Are your fuel filters clean? Is your fuel pump working? Is there air in the fuel system?
2) Air - Is your air intake clear and clean?
3) Compression - Poor compression on a 1-cylinder engine would be pretty noticeable.

After that, it could be other mechanical issue impacting engine performance. More diagnostics can help you narrow things down…

How does it start? Does it idle smoothly? What happens if you give it throttle in neutral? Can you run it in gear? If so, what happens? Any vibrations? How clean is the prop?

There just aren’t a lot of fuel adjustments that need to be made on this engine.

Greg

 

[kloudie1]

The only other thing that is a maintenance item is the valve clearance..It should be checked and adjusted if necessary before any other fiddling with a rough running engine. Many engines today have self adjusting valves and folks forget that small engines don't .

 

[Jim Legere]

As the two previous replies advise, you don't really 'tune' a small marine diesel; you just make sure it is running at specified values. There is no carb tuning, adjusting timing, swapping plugs or any of the tinkering you would do to your favorite hot rod. Fuel metering is fixed, defined by the injector specification. Take the injector(s) to a diesel injection shop for checking, rebuilding. Make sure the fuel filters are clean. Clean fuel is probably the most important thing. Check the valve lash. That's about it.

 

[Benny17441]

One more thing, bleed the air out of the fuel system. Check the fuel lines and connections for any small fuel leaks, where fuel may leak out when the engine is running air will leak in when the engine is stopped. The fuel system does have an adjustable timing for the governor but it is set at the time of manufacturing with different size shims. If you know for a fact that no one has replaced the governor, high pressure pump or messed with the timing then don't worry about it. The only screws you need to worry about is the idle screw as the idle should be set at 750 to 800 RPM. I almost forgot, check the motor mounts as broken or weak will allow the engine to shake and may give the impression it is running very rough. Be careful the mounts may look new but they could be shot. Try to pick up the engine or use a pry bar to lift it at the mounts to check their health. An unbalanced shaft can also rock the engine, especially if the motor mounts are a little weak. Like others have said check compression, the fuel quality, valve lash, clean the injectors and make sure there are no obstructions in the air tube, like broken air filter pieces.