2001 gti revs on its own on the trailer but runs good in the water

[Cheflen]

So I had my 2001 gti out for the first time of the year and it ran perfect. But the next day I hooked it up to the trailer and it idles fine, but as soon as I touch the throttle it just revs up on its own, even if I let off. I'm assuming this is an air leak, but it runs great on the water? What should I look out for?

 

[mikidymac]

You are correct. You need to find the air leak and don't run it until you do as it will be lean and will damage the engine.

 

[Sportster-2001-951C-Stock]

Could very well be an air leak. This symptom (at least for carbed motors) is an indication of a lean mixture thus the carb passages in the low speed circuit might be dirty. Try cranking out the low speed mixture screws 1/4 turn and see if that clears it up.

Also if the fuel tank is running low and there's air in the fuel, so pressure check and make sure the fuel lines are leak free.

And what else - air leaks can happen at the crankshaft seals when they're worn out. Personally, I suspect ethanol fuel isn't helping rubber crank lip seals and plastic bearing cages, it dries them out?

 

[mikidymac]

The most common ones I have seen are the rotary cover o-ring.

 

[Cheflen]

Could very well be an air leak. This symptom (at least for carbed motors) is an indication of a lean mixture thus the carb passages in the low speed circuit might be dirty. Try cranking out the low speed mixture screws 1/4 turn and see if that clears it up.

Also if the fuel tank is running low and there's air in the fuel, so pressure check and make sure the fuel lines are leak free.

And what else - air leaks can happen at the crankshaft seals when they're worn out. Personally, I suspect ethanol fuel isn't helping rubber crank lip seals and plastic bearing cages, it dries them out?

I feel like it could be the low speed mixture screw, when I think about it, it has some hesitation when I punch it from the hole. Do you think adjusting the low speed mixture could fix that air leak? Which way should I adjust the screw?

 

[Cheflen]

You are correct. You need to find the air leak and don't run it until you do as it will be lean and will damage the engine.

I hope it's just the low speed mixture screw, has it had some bogging with low speeds, I'll also have to check the o-ring in the rotary valve. I hope it wasn't that

 

[Cheflen]

I ordered a new carb rebuild kit, and it still had the tempo lines in so I replaced those, do you think that and tuning the carbs to spec will fix it? I'll check the rotary valve o-ring, what should I look for other than cracking/brittle parts?

 

[mikidymac]

I would just replace the o-ring if you have it apart. On a stock ski it should run great on the stock screw settings.

 

[Cheflen]

I would just replace the o-ring if you have it apart. On a stock ski it should run great on the stock screw settings.

So you're saying that this revving on the trailer is most likely caused by a low speed screw out of adjustment? Sorry for the multiple questions, I'm just trying to figure out what I need to order and look out for.

 

[mikidymac]

I would be more inclined to think it is from an air leak. All of the runaway skis I have seen were from and intake air leak or crank seal. On the seadoo's it has been the rotary cover o-ring. It will cost you nothing to set the screws to stock and give it a try. If it runs away just pull the choke and it will kill it.

 

[Cheflen]

I would be more inclined to think it is from an air leak. All of the runaway skis I have seen were from and intake air leak or crank seal. On the seadoo's it has been the rotary cover o-ring. It will cost you nothing to set the screws to stock and give it a try. If it runs away just pull the choke and it will kill it.

That's what I had to do to kill it on the trailer, it gets pretty scary when it runs away even on the trailer lol. I can't seem to find the rotary cover o-ring anywhere, where should I look to buy just the o-ring? It's a 717cc 2001 gti

 

[mikidymac]

Either OEM or I am sure OSD seadoo has them. You can also support our site sponsors pwc muscle. @hfgreg.

 

[Cheflen]

Either OEM or I am sure OSD seadoo has them. You can also support our site sponsors pwc muscle. @hfgreg.

This may be a dumb question but I want to be SURE that the rotary valve cover isn't leaking. Can I put a slight amount of make-a-gasket around the o-ring to ensure a good seal? I am an auto mechanic and understand that less is more when using that stuff, so when I say a SLIGHT amount, I mean a slight amount. Would that work? Just to pinpoint the problem before I start ordering parts? I'm itching to ride and I really don't want to keep waiting for parts

 

[mikidymac]

No. The o- ring should be dry. I understand your impatience but you risk blowing up the engine.

 

[Cheflen]

No. The o- ring should be dry. I understand your impatience but you risk blowing up the engine.

Perfect, that's all I needed to know

 

[Cheflen]

Update: found the problem. There was a bolt MISSING from the rotary valve cover, causing a gap in the cover to allow air in and rev up. luckily I found a bolt laying around the garage and tightened it all up and no more running away on me!