RE: [DML] vacuum problem analysis please!

["John Hervey" <john@xxxx>]

Andy, I cut out a lot of the message to get to the question. Is the enging
hot or cold while performing the test. Also, you can bypass the vacuum
solenoid and go straight to the ignition and see if you have the same
results.
The green air pivot switch or vacuum swithch works off the hot or cold water
in the internal water pipe. When the coolant is cold the vacuum is routed to
the WUR and the vacuum is shut off to the solenoid for the ignition
distributor advance. After the coolant heats up, the valve closes the vacuum
to the WUR and then is directed to the vacuum solenoid for the ignition
distributor. But, If the car is at idle and the micro switch is tripped and
is working, then the vacuum solenoid is electrically shuts off vacuum to
the ignition distributor to advance the timing untill the idle speed
microswitch is dis engauged.
The other problem with the fuel seems to be the WUR allowing the control
plunger in the FD to rise to high creating and enrichment or there is a
vacuum leak which I know you would have checked.
John Hervey
www.specialtauto.com




-----Original Message-----
From: Soma576@xxxx [mailto:Soma576@xxxx]
Sent: Friday, September 26, 2003 5:19 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] vacuum problem analysis please!


F). HOWEVER, when i replace that hose onto the advance diaphragm, i can
feel
that there is vacuum on it (there shouldn't be) and it then shoots up the
advance on the timing. now with the timing wheel on my light at 0 (not
showing
advance) i can see the timing mark way up at like 50 deg BTC. at this
point, the
car runs smoother and better (when advanced and at idle).

3) started inspecting WHY there is vacuum to the diaphragm when the car is
hot. checked the idle speed switch. with a meter, i verified that with the
car
not running, the switch does indeed function when activated (checked ohms).

4) started the engine and with it running and at idle, checked the voltage
at
the electrical connector on the side of the advance solenoid. got a
definite
14.5 volts. this should indicate that the idle speed switch is working
correctly and it is tripped at the proper times. this should also indicate
that
the advance solenoid, if it is not broken, should be energizing AND should
not
allow vacuum to the distributer advance diaphragm. yet it DOES!

what has me puzzled is that this would tend to indicate a broken advance
solenoid. however i replaced this part this summer already (and perhaps i
was the
one who routed those hoses backwards when installing it). i suppose i COULD
have a defective part, but i got it from Grady and it wasn't a used part.

also note that when the car is running, it tends to smooth out for a bit,
then begin to surge a little, then smooth out, etc. the exhaust is very
rich,
too. sometimes when working over the engine it is enough to make your eyes
water a little.

what else should i check in order to rule out other possibilities? the only
conclusion i can come to is that the advance solenoid is broken, but it's
hard
to believe since it is a pretty new part. any other ideas? other tests of
other parts to do? certainly the problem (or at least A problem) is the
presense of vacuum at the diaphragm even when the solenoid is receiving
14.5V from
the idle microswitch. what else could be at fault?

I am at a loss and would like to continue working on this over the weekend,
so if you have a response, please CC it to my actual email address as well
as
to the list so i can get it right away.

Thanks in "advance" (heh heh)
Andy