Throttle not returning to idle

Oily · Feb 28, 2020

For the past month I have been trying to figure out why my throttle wont return to idle and I come to a stop. The RPMs hang at about 2500 even with the clutch pulled in then after a while it drops back to idle.
I have done the following so far
1 Adjusted the throttle cables as per the manual so this is not the issue
2 Lubricated the throttle body links
3 Cleaned up around the butterflies and they are not sticking

I took the bike to the dealer today to get them to take a look and $360 later I still have the problem as they couldnt find the cause.
Here is what they did
1 Re set TPS / STPS STVA Fast Idle system.
2 The mechanic suggested it might be the fuel pump but I replaced this last year with an OEM pump.

Hoping some one on this forum may of had some experience with with this issue or some advice on what to check.

Thanks in advance

Brockie · Feb 28, 2020

It is definitely not your fuel pump. Do you have a Power Commander or any other engine accessory or modification?
I am assuming that the throttle physically returns, but that the engine revs do not immediately drop to idle. Correct?

Oily · Feb 28, 2020

No power commander and throttle physically returns.

slovcan · Feb 28, 2020

That is the classic symptom of a vacuum leak. All the vacuum hoses and vacuum caps need to be checked - or if I was into it that deep I'd replace them (small money for bulk vacuum hose and caps). Another tricky source of vacuum leak can be a carb/throttle body boot. They can look perfect and still have a crack hidden in the corner of the recess where the clamp sits.

Good luck,
Glenn

hoggdoc · Feb 28, 2020

Exactly what came to mind first thing to me too. Isn't a shame you pay big money at these dealers and their mechanics don't know the first thing about how to diagnose a problem unless the plug-in computer tells them where to look. I hope you refused to pay the $360 bill when they didn't cure the problem!

blaustrom · Feb 28, 2020

If you cant find the vacuum leak try spraying small amounts of combustible (starter fluid) at the suspect areas and hoses with the engine running. If there is a leak the rpm's should go up. Carefull to not burn down the bike.

slovcan · Feb 29, 2020

Wow, that is SLOPPY work by the dealer. Your symptoms are classic for vacuum leaks and the dealer missed the obvious. That unseated boot is absolutely part of the problem.

Great job to find that stuff. When you know the vacuum things are sorted out it wouldn't hurt to do a fresh throttle body synch.

Cheers,
Glenn

Throttle not returning to idle

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