slack in throttle

[swordfishman]

I just bought a 2001 SX with 130 hours on it. 
The runs great and looks almost new but the throttle has to be pushed over 90 degrees before the engine begins to ramp up in RPM.  This strikes me as way too loose.  I was thinking a throttle cable clamp had come loose near the control leaver but I would love to hear your opinions.

The only other issue is a bad connection in the amp-meter.  I checked the alternator and it is putting out plenty of juice at a consistent level but the meter wanders and the computer throws alerts.

Cheers and thanks in advance.

[swordfishman]

Wow, I have never been met with silence on this forum before.  Usually it is like drinking from the firehose of helpful comments and ideas.  Now, over 30 reads and no one can even say that my throttle is OK and stop worrying or "yeah, thats a problem.  Good luck with that!". 

[ScarabEpic22]

Well its definitely not right man, Im not sure how to adjust it but you need to for sure.  My 99 E22 has a pretty linear throttle response, once Im in idle and starting to plane gently I can smoothly move the throttle to ~45 degrees and be cruising at 2800-3000rpms.  WOT for me is at about 110-120 degrees past neutral, Im bumping the 6000rpm limiter with my new Acme 541 prop at that point.

Does the engine make a lot of power once you move the throttle past 90 degrees?  Or is it sluggish?

[masonlk]

If I remember correctly mine only moves about 120 degrees total from 12 o'clock back to 8 o'clock or so. How far does your handle travel total to get to wot? What's your rpm and mph at wot?

[swordfishman]

That is what I figured.  I can push my throttle about the same distance as you guys but I max out at 4500ish RPM.  Still plenty of speed and power to board behind but not right.

Have any of you pulled the panel below the throttle?  I took a cursory glance and didn't see any obvious connectors visible.  Any clues for its removal is appreciated.

Cheers and thanks again!

[swordfishman]

OK.  a closer glance and I got it under control.  Thanks for the input guys!

[masonlk]

OK so now explain so that anyone else looking up this problem can find an answer without posting the question again.

[swordfishman]

I still have not figured out the throttle body issues.  What I did figure out is that I did not need to remove any panels to look behind the throttle arm next to the drivers seat.
The behavior is as described previously.  I have to push my throttle arm past 90 degrees before the engine begins to ramp up in RPM.  I can see that the throttle body is actuating in a linear manner (i.e. the end of the throttle body moves directly in proportion with the throttle arm).  I presume there is some adjustment needed at the throttle body.  but have not pursued that yet.  Any suggestion are appreciated.
That is tomorrows task.  I want to get this run to ground before next season.  I might skip winterizing this year.

I intended to purchase a manual for a 2000 GS-400 unless you can get an actual shop repair manual for the SX.

Cheers

[wakejunky]

does the throttle plate open completely at full throttle? what prop are you running?

[lilfoo2225]

theres a service manual on here.

[swordfishman]

The throttle plate does not begin to move until the throttle connecting arm has moved about 90 degrees.  This leaves about 30 degrees of usable throttle.  I pulled the throttle linkage arm.  Then I have about 3/16ths of movement laterally (in/out).  I can rotate this with no resistance for the first 90ish degrees then I seem to feel it mesh with gears and begin to actuate the throttle plate.  I am guessing this is a two gear system or there is some configuration that is required when installing the Throttle position control sensor. 
Has anyone out there ever replaced the Throttle Position Control Sensor?  It is mounted with 3 screws with lock washers but the screws are a very soft metal that wants to strip before it breaks.

Cheers and thanks again all!

[wakejunky]

sounds like you have a bad throttle lever sensor. common failure on the automotive version of the engine. make sure you replace the TLS and not the TPS.

[swordfishman]

Can you confirm part number 2206050020 in Capt. Ricks parts search?  This is referenced as the ACCELERATOR PEDAL POSITION SENSOR in the service manual.  Also, since you have the same boat I do, what year/model Lexus best matches our boats for parts and would this part be ubiquitous between street and marine versions?

[wakejunky]

Yup that's it. and $87 is a smokin deal!!! at the dealership i work for there $200 +. yes street part is identical although the part number is different. reference a 2000 GS or LS 400. parts are the same from 1998 to 2000 in automotive parts

[swordfishman]

Well the $83 dollar price tag was didn't happen for some ill explained reason.  Instead that part was $320 or the entire throttle body for $420.  So I am opting for the entire throttle body.  I hope to have this on order by Monday.  I will tear apart the old throttle body and see if I can get some form of forensics on the actual failure of this part.  The boat only has 130 hours on it and looks like new.