Turn on ski - goes to 6k rpm (while at "idle")

[tweakmeister]

As the title states, I turn on the ski (SLT750) and it slowly builds up to 6000 rpm without touching the throttle. The throttle cable is not stuck and the throttle plates are all closed.

Ski specs:

-Fresh carbs (all SBT goodies!)
-New gaskets all around the intake area
-Needles/Pop-off pressure are perfect
-Backed the low speed screws off an 1/8th from spec
-New reeds
-New plugs
-Fuel lines all good
-New fuel pump
-Full battery
-Excellent compression all 3 cylinders
-Doing pre-mix with SBT block-off plate (good seal)

It seems like there is either an air leak (how small of a leak could cause this?) or the low speed screws need to be fiddled with more.

Could it be anything else?

[Technical Support]

Re: Turn on ski - goes to 6k rpm (while at "idle")

You're on the right track. You can strap it to the trailer and idle it, then spray starting fluid around everything to try and find your leak.

[tweakmeister]

Re: Turn on ski - goes to 6k rpm (while at "idle")

I fiddled with the screws a bit more - I can get the ski to start fine, but it build up again over the course of 30 seconds to a minute and likes to be around the 4k-6k range (I shut it off once it starts to climb).

I'm going to pull everything off and spray all the new gaskets with some kind of Permatex. I can't believe a pin hole leak would cause it to run to 6k though?

edit\\\

I've been reading these forums and seems like there are a lot of potential solutions but no easy pin-point cures. As with some previous troubleshooting items, I'm going to start from the beginning and work my way through the system (fuel tank to lines to valve to fuel pump...).

[VaSuperjet]

Re: Turn on ski - goes to 6k rpm (while at "idle")

Yep, you may have a leak in the fuel system causing a lean out. If it starts easy then I'd lean more toward an air leak. Just for kicks though bypass the fuel system and go straight from tank to carbs, also check the return line and make sure it is not clogged. SBT is right though, you should do this in the water with the ski in the water still tied down to a trailer. This will help prevent a runaway motor that will ruin your day and also put a load on the motor to better feel the motor and allow you to use the throttle a little. Check the pulse line for the carbs, it can be a culprit too and cause a major air leak.

[tweakmeister]

Re: Turn on ski - goes to 6k rpm (while at "idle")

Appreciate the advice.

Got it to idle correctly in the driveway (one of the jet o-rings had sheared and was leaking...easy fix thankfully...).

Despite living next to the sailing capital of the world, there are no launch ramps where I can leave the ski on the ramp and tune it. Everywhere is a protected 5mph zone (which is fine...I can idle out and then swap plugs to tune hi-speed), but then most of the local marinas switched over to annual fees, which means $300 just to launch the ski and see if it works :emoticonw

I found some back creek that it's the middle of no where. There are signs up about a sewage spill (no swimming), but water is water...

I hope she works...something tells me it still won't work correctly under load, but I hope rebuilding the carbs was the fix to my problems starting a few years ago :beer (I have some old threads on here about it).