Re: Vacuum Switch troubeshooting (was amazing vacuum discovery

["Dave Swingle" <swingle@xxxx>]

Couple things - I just spent a short while troubleshooting the same 
device. It's an electrically operated vacuum switch. Controlled by 
the idle microswitch. 

1 -this should have no effect on your CO setting.

2- there is a right way and a wrong way for the hoses to go on that 
switch. Make sure that the distributor is connected to the outside 
(back) connection, and the source to the center one. Backwards you 
will get a vacuum leak at idle and the distributor vacuum will "hang" 
when you drop back to idle. Emissions problem. 

3- This thing is prone to vacuum leaks where the wires connect. Put 
some RTV around the electrical connection. 

4 - the vacuum switch is controlled by the idle microswitch. With the 
ignition on, put your hand on the switch and pull the throttle on and 
off idle. You should be able to feel it click. 

5 - Hook up a vacuum gauge to the inlet side of the switch. Start the 
car COLD. There should be no vacuum until the water gets to about 
100degF -in my case this took about two minutes. If this does not 
happen you have a bad temperature switch, unfortunately located UNDER 
the intake manifold in the PRV Valley of Death.

6 -Now hook the switch back up to the vacuum source and hook your 
gauge to the outlet(dist) side. You should see no vacuum at idle, 
then pull the throttle slightly off-idle, you should get vacuum 
immediately. If not, check the vacuum switch wiring and/or replace 
it. 

If you get this working right you'll notice a significant increase in 
fuel economy. 

Dave


--- In dmcnews@xxxxxxxxxxxxxxx, Soma576@xxxx wrote:
> List,
> 
> 
> well yesterday i was doing some cleaning and i knocked the vacuum 
hose that 
> goes from the thermal control valve to the middle orifice on the 
vacuum advance 
> canistor/solnoid behind the fuel distributor. the hose felt a 
little loose i 
> cut a bit off of it to give some fresh hose to the fitting. lo and 
behold, 
> inside the part i cut off there was a little BALL BEARING wedged 
into the hose, 
> apparently to correct some problem by cutting off vacuum years ago 
that a 
> previous owner/mechanic did. great......
> 
> now my car idles at around 950 (used to be 775) and when it is hot 
the idle 
> sounds kind of squirrelly. this is terrible because i think i have 
been 
> working around this BS for years and now is EVERYTHING out of wack?
> 
>i found this 
> 'problem' and 'corrected it'. i expect to have to get the timing 
adjusted, but 
> what else will have to be done now? the book says timing should be 
checked at 
> 775 rpm. i am a couple hundred higher than that. will that make a 
> difference? how do i get the idle back down again? will my CO have 
to be adjusted again 
> (i drove 300 miles to get it done)?