Yanmar GM1

[Griffiths]

My yanmar GM1 runs OK when not in gear but as soon as I engage either forward or reverse gear the engine will run at about 1/4 of its revs, I have replaced all the filters and replaced the deisel and olso put injector cleaner in the tank.
I have not had the injector serviced as all my yachting budies insist that is not the problem can anyone help?? Many thanks

 

[Pye_End]

Was the fuel in the filter good and clean? Do you collect any water in the separator?

If it turns out not to be fuel or air, then worth checking exhaust bend (you'll need to take it off). Mind you, it ought to be checked every few years anyway.

 

[ShipsWoofy]

I don't mean to state the bleedin obvious, but have you tried turning the shaft by hand with the engine in neutral? Is the prop jammed up or the shaft?

Look for the most obvious bits before starting to strip the motor down.

Turn the engine with the starting handle, compression off obviously, then pop it into gear, can you still turn it?

 

[Griffiths]

Yes all the filters were clean and no water in the seperators ,you think it could be a problem with the exhaust even though it revs freely when not in gear ?
| have tried the shaft and it is free to turn. Thanks

 

[Pye_End]

When there is no load on a diesel it is pretty easy to rev, so not a very useful means of diagnosing problems.

Have you checked the air filter?

What does the exhaust colour look like (under load)?

Is the prop clean or covered in growth?

The 1GM10 does suffer from corroded exhaust bend. If it fails it is possible that you are looking at 'heart surgery' so it is worth checking.

If you do a search on this on the forum you will find several threads on exactly this sort of problem with this engine.

 

[Rabbie]

I had a similar sounding problem on my 1GM and found it to be the locking-screw (loose) at the engine end of the throttle-cable, causing it to 'snatch' or 'slide' as the cable was slightly distorted. Easy fix.

 

[mainmarine]

You could check here to see if someone has had a similar problem: http://www.yanmarhelp.com/

 

[tyce]

have a look at the posts about the governor spring on the yanmar help forum, sounds like it may be the culprit

 

[lw395]

Does it smoke when it refuses to rev?
black smoke=xs fuel, xs load,
no smoke suggests lack of fuel. check for air leaks in fuel line, liftpump etc.
Also previous post was valid, does the regulator arm actually move as far when in gear.? could be problem with morse throttle/gear assy. try prodding the lever at the injector pump, does it respond or is it on the stop already?
Then theres all the odd possibilities like tank breather restricing fuel flow (this would take time to show itself?)
Good luck with it anyway!