Date:         Tue, 16 Sep 1997 13:44:27 EDT
Reply-To:     Sean Bartnik <sbart7kb@WWW.MWC.EDU>
Sender:       Vanagon mailing list <Vanagon@Gerry.SDSC.EDU>
From:         Sean Bartnik <sbart7kb@WWW.MWC.EDU>
Subject:      Re: Problem recreated under static environment (was more
              problems) (fwd)

David,
A way to test your theory would be to simply disconnect the electrical
connection from the cold start valve and see if your problem continues.

Here's how the cold start valve/thermo time switch works:

The thermo-time switch has a metal contact arm inside which is wrapped
with a heating element.  When it's cold, the arm contacts a ground
connection.  When you turn the key to start (the cold start valve ALWAYS
receives power when the key is in start, and ONLY when the key is in the
start position -- temperature is irrelevant as far as the cold start
valve itself is concerned) 12v is sent to the cold start valve.  If the
thermo-time switch is cold, then the thermo-time switch grounds the cold
start valve, allowing it to inject fuel.  When the key is "on" the
heating element in the thermo-time switch is warming up and slowly
bending the contact arm, and so once it gets warm enough, it breaks
contact and no longer grounds the cold start valve, shutting it off.

However, this applies only when cranking.  The cold start valve never
receives 12v when the engine is running, i.e. when the key is in the
"on" position, only when the key is in the "start" position.  So, to
answer your question, no, the cold start valve is probably not staying
on, unless you've got some weird wiring.

And the thermo-time switch does not supply 12v to the cold start valve,
it merely supplies a ground for the cold start valve.

Sean

>
> Ok, for those of you following this thread, here's the latest.
> Went out this morning (approximately 68 degrees F) and started the beast
> up, no problem.  Let it idle until warm (approximately 10-15 minutes)
> and then shut it off.  Let it sit for approximately 5-10 minutes and
> then restarted it.  Ran crappy, heavy fuel smelling smoke.  Shut it off
> and took the #2 temp sensor out (again).  Cleaned the area around the
> seat with a piece of sand paper until it shined.  Cleaned the interior
> threads of the hole with a little solvent and dried.  Reinstalled the
> sensor and checked with my ohmeter.  Checked out ok.  Started van, still
> ran crappy.  Let it run for approximately 10 minutes (or so) and as
> quick as it had started, it ended.  I am beginning to suspect that the
> thermo time switch is sticking on and continues to operate the cold
> start valve even after engine is warm.  Of course, with outside
> temperature already above 80 degrees F I cannot do the test per Bentley
> until tomorrow.  Question.  If I disconnect the cold start valve and
> close the circuit with a test lamp, if the thermo switch operates, tries
> to open the cold start switch, lights the lamp thinking that the switch
> is open, no extra gas goes into the air mix and the running rich problem
> is fixed (temporarily) until I can replace the thermo switch.  Does this
> make sense, or is my VW addled brain reaching for straws?  Any input?
> --
> Chaz
> "I'm growin' older, but not up"
> '82 Westy "Peewee"
> Brownfield, Texas
>


--



--