Idling too fast

[carlager]

The idling on our Yanmar 3gm30f has suddenly increased to 1.600rpm when starting the engine with the handle In idle position. The handle has also become harder to push in forward position and now needs to be pushed to 90 degrees to achieve full speed

How do I adjust this on the screw on the cable ?

 

[petersea]

It sounds more like a cable gone bad then a adjustment issue. First thing to check is disconnect cable at engine side and check operation. If cable is operating like it should then check the fuel pump, either the idle set screw has creep and needs readjusting or and this is common on 3gm engines the throttle shaft shaft has become rusted stiff and will need to be cleaned up and lubricated. Most likely if it is rusted stiff you will need to fix the water leak just overhead from the fuel pump some times there is a very slow drip right onto the fuel pump shaft area that cause this. Both of these are simple jobs. If the cable is stiff and not moving back and forth freely you can try some penetrating oil from both ends. If that helps then follow up with some cable grease. You will need to remove cable at both engine and control sides to check. If all of the above are working correctly there is usually a adjustment screw on the controls (check manual) and it will need to be backed off. My gut feeling is you need a new cable now or in the very near future either way. But need to do some more diagnoses first. Good Luck and let us know the outcome.

 

[kloudie1]

I agree, I would first check the cable down at the engine. The little bronze block in the picture is the cable end attached to the governor control arm (throttle?) Just below the block is a screw and nut. That is the idle stop adjustment. With the engine not running, put the pedestal lever to idle and then look at that arm and screw. The little arm should be touching the top of that stop screw. If it is not, pull the cable forward until it does, then verify that the engine idles at correct speed. Most likely, the cable housing is slipping in either the clamp on the engine or the one in the pedestal ..

 

[carlager]

@kloudie1

You Are rigth

 

[carlager]

The photo shows that the arm does not touch the screw when the handle is in neutral.

Moving the handle forward the arm will touch the screw.

Should the idling be normal when starting the engine in this position ?

 

[kloudie1]

Idle Stop

Carl, that screw should slide freely through the cubical part and should be held against the end by the spring. Hit that with a little WD40 then put a couple of drops of motor oil on it to make it move freely.
Here is another shot showing where the lever stop is for Idle.. If the nut is not being pushed forward by the spring, the lever won't be touching this stop screw at the bottom..
You should start the engine with a little throttle off idle, but you should be able to go to idle immediately after the engine cranks up.

 

[carlager]

The screw slides freely through the cubical part. I have however given it some w40 on your recommendation.

The lever does NOT touch the screw as in your photo. Could that be the culprit ?

 

[carlager]

This is how it looks with the handle in neutral. As you can see the screw does not touch the lever

 

[Charles Erwin]

Your picture shows the spring fully compressed.

That spring should push (slide) the outer square block forward over the inner adjuster. It should not be compressed - it should be fully extended.

That means that the spring is broken, something is preventing the block sliding forward on the inner adjuster, or something is in the path of the lever thus stopping the lever from swinging fully forward to the stop screw.

Charles

Edit - See if you can pull the lever forward so the block moves forward thus expanding the spring?

 

[carlager]

Charles,

The lever can be put forward manually by hand.

When this is done the engine runs at normal idle speed (875 rpm) and the cable looks in the photo.

The springer does not look broken

I will however need to unhook the cable and start the engine to find out if the culprit is the cable or something obstructing the lever

 

[carlager]

@Petersea
You were spot on.

The lever (throttle shaft) on the engine is hard to move to idle position caused by as you wrote a water leak from the seawater hose above the shaft area.

Being a newbie on this I will have a Pro clean and lubricate the lever and fix the water leak


Thanx a lot to you and everyone else for helping with this

 

[kloudie1]

Good Job, Carlager. If you have a single lever control for speed and transmission, get the mechanic to check that out as well. Good Luck .

 

[petersea]

@Petersea
You were spot on.

The lever (throttle shaft) on the engine is hard to move to idle position caused by as you wrote a water leak from the seawater hose above the shaft area.

Being a newbie on this I will have a Pro clean and lubricate the lever and fix the water leak


Thanx a lot to you and everyone else for helping with this

This is something you can do yourself even being a newbie.. Get a can of PB buster penetrating oil (this stuff stinks but works great) spray the shaft area let sit a little while then work shaft back and forth. After shaft is free lubricate (coat liberally) with some white grease of other waterproof type grease. As far as the water leak sometime a second clamp will stop it and if not drain system and remove hose (depending on age and condition may be time for a new hose......... something to check) and i reinstall with a coating of permatex blue type gasket sealer on the neck and double clamp. Whole job should not be more then one hour total time plus clean up, Good Luck and glad we were able to help.