Fast Idle 87 5ktq

["Doyt W. Echelberger" <Doyt@nwonline.net>]

This 87 5ktq at 160k idles at 2,000 RPMs after warmup. It starts fine,
idles cold at about 1,200, and then RPMs keep climbing as it warms up.
When warm, I can turn the idle screw down to 'closed'(from a setting of
about 1/4 turn) and it doesn't affect anything. 

After it warms up, I can get it to idle at 750 very smoothly by
disconnecting the electricals of the ISV. It continues to idle at 750 if I
then reconnect the ISV electricals. This puzzles me and is why I elected to
post to the list.

The same day this fast idle appeared, I had followed Scott Mockry's advice
about resoldering the internal connections of my throttle switch. I did the
work and replaced the switch and set its position by rotating it
counterclockwise until the microswitch clicked, and then locking it there.

I suspect that the fast idle is a result of the positioning of the throttle
switch, but I thought I'd confirm this hypothesis by consulting with the
list before tampering with all those components. Resoldering the throttle
switch noticeably improved acceleration response, so Scott was right on
when he said ALL the old throttle switches are probably running with
fractured and inconsistently working internal connections. One of my
connections was totally covered with brown crusty stuff, which probably
indicated longstanding problems. The other 3 looked pretty clean, but I
resoldered them anyhow.

OK, there it is.  Replies and speculation appreciated. About all I can
think of is to fiddle with the throttle switch rotation, and clean the ISV.

Doyt Echelberger
87 5kcstq