The idle valve should always hum.  You might have a bad idle control unit.
I had to replace mine.

Pat Callaghan Jr.
87 Westy GL
Portland, OR.
www.cybcon.com/~patcal

----- Original Message -----
From: "Richard Golen" <rgolen@UMASSD.EDU>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, April 19, 2003 6:45 AM
Subject: Does Idle Stabilizer Constantly Stay On?

> Hi,
>
> Just when I think I've solved the bad idle problem in my 87, it developed
a
> new behavior. I swapped out the idle stabilizer with my wife's 90
> cabriolet. The rough idle/rich mixture problem at start up seemed to go
> away. But then after a day or so, it would idle at 2000 and stay there. I
> shut off the key and quickly turn it back on and the idle would drop to
> normal, but eventually get back to 2000.
>
> So I out the original idle stabilizer back in the 87...but before doing
> that I cleaned it with carb cleaner as suggested by someone on the list.
> The 87 ran ok for a few minutes then after I drove it around the block a
> couple of times, the idle went back to 2000.
>
> I've noticed that the stabilizer constantly "hums". Is it supposed to shut
> off after a while?? I disconnected the stabilizer and opened up the air
> bleed screw on the throttle body, and it seems to idle ok now.
>
> This is getting frustrating!!
>
> I also cleaned the ground connections for the oxy sensor in hopes that
> would help....
>
>
> TIA
>
>
> Ric
>