Yanmar Throttle Not Holding

[colb218]

Hello All-

I have what feels like a silly question. I have a Yanmar 3HM35F that starts right up every time. Occasional puff of smoke on start up, but otherwise seems to run fantastic with no issues that I can tell. I have been running it at roughly 2200 RPM as that pushes me along at close to 6 knots on calm days with around .75g/hr consumption. All seems good.

Well, reading the manual I see my continuous rating is 3200 RPM and my 1 hr is 3400. I read that running at lower RPMs can be detrimental so I have been attempting to run at higher RPMs. Occasionally I am able to get the RPMs up to roughly 27-2800 RPMs, but what I find is that my throttle tends to slip back down to the 2200 range when I let go of the throttle control. In other words it runs fine at my desired RPM, it just slips back down to the lower RPM with out physically holding the throttle in place.

Is this some mechanism in the engine to prevent over reving when not up to temp? Or is this simply that my throttle cable is not holding the desired location? I do find that if I hold the throttle in place at my desired RPMs for a few seconds that the chances of it staying in place are better than if I rev up and let go.

FWIW my throttle/shift levers are very basic. They are both basically flat stock mounted vertically on the sides of my pedestal. Pull up on the shifter to go into reverse, push down to go forwards. Throttle is pull up to increase revs and push down to return to idle.

 

[Stu Jackson]

The adjustment is usually inside the pedestal, not necessarily on the engine, while there could also be a friction adjustment on the engine, too.

 

[kappykaplan]

Look for a cable clamp on the throttle cable. Should be able to tighten just a little.

 

[kloudie1]

Look for a clamp like this: Morse Controls Throttle Cable Brake - for 30, 40 & 60 Series Cables (sailboatowners.com)
on the throttle cable .. it might be close to the engine end of the cable.. If ya don't see one, then ya need to install one like this.

 

[colb218]

Thanks for all the replies. Glad to hear it is something simple!

 

[Tally Ho]

On my O’Day 322, with an Edson pedestal, there is an adjustable clamp inside the top of the pedestal to hold the throttle in place.

Greg

 

[colb218]

Good news everyone! I did an oil change this last weekend and noticed that my throttle cable had a clamp similar to what was posted above.

Tightened down each nut about 1/2 turn and when I restarted the engine after changing the oil the throttle felt so much better!!

 

[kappykaplan]

Good news everyone! I did an oil change this last weekend and noticed that my throttle cable had a clamp similar to what was posted above.

Tightened down each nut about 1/2 turn and when I restarted the engine after changing the oil the throttle felt so much better!!

Well done!

 

[sailcapt340]

You didn’t say where you found the cable brake along the cable. I found placing the brake within a foot of my throttle handle inside the pedestal works so much better than further down the cable in the engine compartment.
It holds my handle in place at all RPM‘s.
What was happening inside my pedestal was “cable whip”. The loop just after the handle was whipping each time I adjusted my speed and that caused the handle to throttle back on its own.
I thought I would add this to the conversation in case you aren’t getting the hold you want.

 

[colb218]

You didn’t say where you found the cable brake along the cable. I found placing the brake within a foot of my throttle handle inside the pedestal works so much better than further down the cable in the engine compartment.
It holds my handle in place at all RPM‘s.
What was happening inside my pedestal was “cable whip”. The loop just after the handle was whipping each time I adjusted my speed and that caused the handle to throttle back on its own.
I thought I would add this to the conversation in case you aren’t getting the hold you want.

oh!! good to know. well as fate would have it I opened my engine work area and low and behold it was sitting right in front of me. So not very near my pedestal.

I will play with it next time I go out and change it further if needed

 

[sailcapt340]

Glad you found it. The throttle slipping back is one very annoying problem to have on a boat. And it gets tiring holding it in position while steering. It should solve this issue for you.

 

[smokey73]

Hello All-

Well, reading the manual I see my continuous rating is 3200 RPM and my 1 hr is 3400. I read that running at lower RPMs can be detrimental so I have been attempting to run at higher RPMs. Occasionally I am able to get the RPMs up to roughly 27-2800 RPMs,

.
Next question to ponder is: Why can you only get up the RPMs up to 27-2800 RPMs when your 1 hr rating is 3400 RPMs. You should be able to get to close to the rated RPM unless you are over-propped, the drivetrain is fouled, or the prop/hull needs cleaned. Just asking?

 

[colb218]

Good Question... honestly I have not felt the need to run the engine at the higher RPM. With the throttle cable issue address I think we will prob work harder at getting the rpms higher. I have not run out of RPMs... but also haven't tried

 

[smokey73]

The first and easiest thing to do is get or borrow a digital handheld Tach. They are relatively cheap and easy to use. Then see first if the tachometer on your engine panel is reading correctly. If everything is set up correctly for the tach sensor then the digital hand held tach and your panel tach should be fairly close (maybe not exact but not off by 600 RPM.) After that it is a matter of deciding "if you care" I am not sure of the impact on the drive train, fuel consumption, etc is. Other's can weigh in on the impact of being "over propped" (ie the prop size or pitch is not properly matched to the rest of the drivetrain.)
'-