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-   -   Yanmar 2GMF, throttle return spring too strong (http://www.sailnet.com/forums/diesel/105025-yanmar-2gmf-throttle-return-spring-too-strong.html)

rauschpfeife 10-24-2013 04:47 PM

Yanmar 2GMF, throttle return spring too strong
 
I recently acquired a Pearson 303, vintage 1983, and I'm still getting to know it. Yanmar 2GMF inboard.

A curious problem: the throttle appears to have a return spring, or something similar, which tends to push the throttle back down to the idle position. There is a sort of clamp on the throttle cable housing, which creates enough friction in the cable to oppose this force. But if I clamp the cable hard enough to keep the throttle in the fully-open position, it's so clamped-down I can't move the throttle at all.

There doesn't seem to be any obvious way to adjust the tension on the return spring, or whatever it is, which seems to be *inside* the engine. Is that possible?

Anybody ever encountered this problem? Suggestions?

PS -- Been looking at the service manual, and I'm starting to get a sinking feeling that all this magic happens inside the injector pump... Somebody tell me I'm wrong!

capttb 10-24-2013 05:37 PM

On an Edson pedestal there is a bolt to adjust the tension on the throttle lever under the compass.

rauschpfeife 10-24-2013 05:43 PM

Re: Yanmar 2GMF, throttle return spring too strong
 
I looked but didn't see one; will look again. It kinda appears that spring tension
is needed from another source to balance the idle-ward internal tension in the fuel system itself.

arf145 10-24-2013 07:11 PM

Re: Yanmar 2GMF, throttle return spring too strong
 
capttb has it right. I had that problem with my Pearson. Assuming you've got an Edson pedestal, the screw is inside where the speed control comes through. Tighten that set screw a tiny bit --it doesn't take much.

redline 10-29-2013 11:53 AM

Re: Yanmar 2GMF, throttle return spring too strong
 
On my C&C33 I looked and never found a throttle friction adjustment on the Edson pedestal. What I did find (with help from the person who sold the boat new) was a small u-bolt on the cable which needed a tiny bit of tightening. Always found it odd, but it worked, even though the "adjustment" was a bit touchy.

capttb 10-29-2013 12:57 PM

Re: Yanmar 2GMF, throttle return spring too strong
 
The following is from the FAQ page from Edson:
Quote:

Q4: My throttle doesn't hold when I push it full forward - what can I do?
A4: Some Engine have a very tight spring on the throttle lever. Depending on the Engine Control Model, you may be able to tighten the Throttle Friction Adjuster. Older controls may not have this adjuster, but a "horseshoe" cable-clamp can easily and inexpensively be clamped around the outer jacket of the engine control cable to add the proper cable resistance

wduncan50 10-29-2013 02:23 PM

Re: Yanmar 2GMF, throttle return spring too strong
 
I had the same problem on my hunter and had to buy a boat trottle cable brake. It's cheap and simple.

Teleflex Cable Brake - Star Marine Depot

Faster 10-29-2013 02:40 PM

Re: Yanmar 2GMF, throttle return spring too strong
 
Quote:

Originally Posted by wduncan50 (Post 1111893)
I had the same problem on my hunter and had to buy a boat trottle cable brake. It's cheap and simple.

Teleflex Cable Brake - Star Marine Depot

You can make your own with a split piece of small hose.. firmly clamp it on the outer sheath with a hose clamp, and lightly clamp the other end on the sliding part of the cable.. adjust the latter tension for the friction you need.

You can do this at either end, whichever is most accessible.

rikhall 10-29-2013 04:10 PM

Re: Yanmar 2GMF, throttle return spring too strong
 
A common problem, a very cheap fix:

https://lh5.googleusercontent.com/-f...s500/cable.JPG

This was on my brand new Yanmar 2GM20F.

Just tighten until is stays where you want it when you adjust it.

Rik

redline 10-30-2013 10:46 AM

Re: Yanmar 2GMF, throttle return spring too strong
 
If adding a clamp on the cable as pictured above (or the Teleflex version), it's best to put it as close as possible to the control lever end of the cable. If the cable length is significant and/or has several bends, it will add "sponginess" if the clamp is at the engine end.

Also, it shouldn't be too tight - ideally the return spring should throttle the engine back to idle if the control cable somehow let go.


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