GT40 Throttle Backs Off

[rcsmith727]

My '95 Super Sport consistently slows down at speeds of more 15 mph. It's been happening since I hit a log @ Ozarks last week. Seems like the PP isn't keeping up?

I replaced the throttle cable last year and upgraded to PP Stargazer this year. Should I adjust the connection of the cable at the throttle body?? Maybe the return spring is weak.

In the PerfectPass, I tried lowering the KDW setting and it didnt help, so I keep it around 85 KDW. Maybe I should try a higher setting? Also did a diagnostic run and everything seemed fine.

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[sbaker]

A couple of questions to help diagnose:

does this happen when you don't have PP on?

dave you inspected the throttle cable tightening of the PP when you turn on the ignition?

[rcsmith727]

Quote removed by Admin for not following the Guidelines for Quoting Previous Posts in a Thread.

Yes, it happens even when PP is turned off. Doesn't the servo motor keep the cable tight when the system if "off" though?

Yes, I ran PP diagnostics and it tightens at start-up. It does really well when we surf - I can keep a steady speed of 10 mph no problem. It really only happens when we speed up to wakeboard, which seems odd...

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[sbaker]

Yes, the servo motor is designed to keep it tight.

I've had some cases where my GT40 lags a little bit getting up to plane (and eventually it gets to the PP speed) when wakeboarding and running a total of ~1000 lbs of ballast but this doesn't sound like the same issue.

Since this happens without PP, I'd be temped to see what happens when you put the boat on a fake-a-lake/hose and manually pull the throttle body right on the motor (to rule out any slop in the throttle lines)? If you're able to keep a constant RPM with that, I'd maybe start to think about engine/tcase/prop issues or just losing power, which would lead to a bunch of other diagnostics (like seeing if there are any cylinders misfiring). How does the engine sound when running at a constant RPM?

[Tom_H]

Slows down without the throttle arm moving, or has your throttle arm lost tension and is walking back? If it's slowing down without the throttle walking back, I'd check your throttle cable connection on the motor end. I'd venture that it's loose and letting the cable sheath slip in the clamp resulting in your speed loss (could have gotten jarred loose when you hit the log). Could have an issue on the throttle side as well, but would put my money on the engine side of the cable.

[rcsmith727]

Slows down without the throttle arm moving, or has your throttle arm lost tension and is walking back? If it's slowing down without the throttle walking back, I'd check your throttle cable connection on the motor end. I'd venture that it's loose and letting the cable sheath slip in the clamp resulting in your speed loss (could have gotten jarred loose when you hit the log). Could have an issue on the throttle side as well, but would put my money on the engine side of the cable.

The throttle arm walks back, so I'm constantly having to push the throttle forward again. It's almost like the PP auto tension is just pulling it back too much?

I liked sbaker's idea to run it on the fake lake and see if it does the same thing without the prop spinning. I'll hook it up as soon as I can. I'm too busy with kids schedules this week...

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[Tom_H]

If that's the case, then check your control for a tension adjustment. Or you can put a cable clamp on the throttle cable to add some drag and keep the throttle in place (had to do that to my old Morse control)

[windsurfnut]

Is the lever physically moving?

On the PP servo, the black knob, there is a set screw that can come loose and messes with the cable tension. Check it, follow the winding instructions (power off) to tighten up the cable then retry. Happened when I got my new to me 2002 SN and I thought I had broke the boat the first day.