Sticky throttle only while in gear - dealer could not fix

[durdy]

I've had this into the dealer 3 times to repair, 3 times got it back no change. I'm going to the forums for hopefully an explanation as to what's going wrong and a fix.

Volvo 4.3, SX drive.
When in neutral (button pressed), the throttle lever moves easily. A light touch is all that's needed. Resistance is easily controlled by adjusting the friction screw.

When in gear, the throttle is heavier but usable for most things. Larger movements in the throttle are ok (e.g. holeshot). Slow speed adjustments like while docking are also quite fine, including switching between forward, neutral, and reverse, again small movements around the vertical position of the shifter.

Issue is small adjustments in throttle while underway. The throttle is near impossible to budge for making small movements. It's very very sticky - moving the throttle small amounts is difficult to control, usually requiring bracing your forearm against something and pushing in a controlled way. Or using both hands. The throttle doesn't want to move initially. When it does move, there's an audible "tick" sound and the movement is usually more than you want. Small speed adjustments while towing a skier or boarder are extremely difficult.

If the throttle cable was sticky I would've expected it to be sticky in neutral too. It isn't.
If the shift cable was sticky I would've expected issues moving between forward/neutral/reverse. No issues there.
It's only while in gear and at moderate throttle and above when there's the incredible annoying stiction.

Would love to know what's going on here. Thanks.

 

[ahicks]

First thought here is that the something is going on to change the throttle cable when the motor is under a large load. Is there enough slack in the cable to allow the motor to shift a little as it takes up slop/add torque on the motor mounts? Is there a chance you might have a loose or broken motor mount that's not showing up with no load on the motor?

I hate dealers....

 

[Scott Danforth]

most likely its your shift cable that is rusted up and needs replacing. especially if the throttle only button is smooth as butter.

that "tick" you hear is the rust breaking loose.

 

[ahicks]

most likely its your shift cable that is rusted up and needs replacing. especially if the throttle only button is smooth as butter.

that "tick" you hear is the rust breaking loose.

Explain please. His note clearly states it's shifting easily. "If the shift cable was sticky I would've expected issues moving between forward/neutral/reverse. No issues there."

 

[Scott Danforth]

ahicks re-read post #1.

when in neutral, the throttle moves easy
when in gear, it doesnt
when going between neutral and forward/reverse, that little transition is neutral, until you move the throttle lever forward or back, then you are moving the shift cable.

 

[ahicks]

That doesn't change this-
"If the shift cable was sticky I would've expected issues moving between forward/neutral/reverse. No issues there."
Not in my mind anyway.

 

[Scott Danforth]

That doesn't change this-
"If the shift cable was sticky I would've expected issues moving between forward/neutral/reverse. No issues there."
Not in my mind anyway.

pull the control apart and look at the progressive nature of the shift cable and throttle and it becomes clear. guarantee that if the OP disconnects the shift cable from both ends, he wont be able to actuate it without putting a large vice grips on the cable. I also bet that the end at the drive is all rusty and the cable is split.

 

[durdy]

Thanks for the replies. Couple things, the throttle has been like this since the boat was new. Also the audible 'tick' when overcoming the stiction is coming from the control so if it's rust, there's at least rust on the non-drive end of the cable.

I haven't taken a control unit apart nor have I seen a good diagram of how it works internally. Once engaged say in forward gear, does moving the lever further forward continue to pull the shift cable along with the throttle or is the mechanism such that the shift cable only moves enough to engage the gear then subsequent forward movement of the lever only articulates the throttle? If the latter then the problem may be the control.

 

[Grub54891]

Just finished one up with similar issues. Guy brings the boat in and said replace all the cables, they are old and stiff. Four cables, 23 foot run. When the cables were all removed the shifter looked and felt perfect. After replacing all the cables it was still stiff as all get out. Had to replace the controls also. Solved the problem. Under load it would bind up but I even tried lubing the control, no difference.

 

[ahicks]

Thanks for the replies. Couple things, the throttle has been like this since the boat was new. Also the audible 'tick' when overcoming the stiction is coming from the control so if it's rust, there's at least rust on the non-drive end of the cable.

I haven't taken a control unit apart nor have I seen a good diagram of how it works internally. Once engaged say in forward gear, does moving the lever further forward continue to pull the shift cable along with the throttle or is the mechanism such that the shift cable only moves enough to engage the gear then subsequent forward movement of the lever only articulates the throttle? If the latter then the problem may be the control.

The shift arm/cable only moves far enough to engage the gear. There's no further movement from that point.