Thread: Vapor lock
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356-930 356-930 is offline
Acceleration Junkie
Join Date: Aug 2007
Location: Laguna Beach, CA
Posts: 263
Originally Posted by TDH888 View Post
Dear 356-930 and other responders to this post,

I would like to give you an update as to whats happening w/ my car in the hands of my mechanic. First of all we replaced the ignition coil because the original coil was already leaking w/ oil at the top edges. I replaced it temporarily w/ a working Bosch coil and the car idles & run better. I ordered the proper one from pelican & it will arrived next month. I believe the ignition coil we replaced was w/ the car since 1989. We also discovered that the socket that connects to the CDI was loose. We discovered it when we were trying to start the car 30mins after shutting down then restarting it. While I was cranking car what he did was to wiggle the connector going to the CDI and the car started at once. We reconnected the cold start valve . The mechanic tightened the CDI connector. He tested the car bringing it to operating temp. We shut off and restarted the car after 30 mins ,the car refuses to start . He disconnected the connection immediately going to the cold start valve and the car immediately started. My thermo time switch is new it was replaced 2 months ago and its specific for the 89 930 USA version. Do you think my cold start valve is the culprit?

No, I do not believe the cold start valve or the thermal time switch is the problem. Re-read my information on how the thermal time switch (TTS) works. Bottom line, if engine is cold, TTS turns the cold start valve on and fuel flows into the intake manifold. If engine is hot, TTS does not turn cold start valve on. If the TTS were "bad" meaning it turns the cold start valve on even when the engine is hot, the engine would most likely sputter to life because it was too rich but it would sputter to life. If so rich it couldn't start, you will smell raw fuel in the exhaust pipe.
The minute you let go of the starter motor, (i.e. stop cranking the engine) the TTS and the cold start valve, whether good or bad, are out of the circuit. Neither will have a +12v supply. If you're cranking and cranking and it's not starting hot, you probably don't have fuel.
As suggested by Pat Keefe, "Check the residual pressure in the fuel system after you shut the pumps off, and see if it is to spec for that time period specified. If your pressure drops off real fast, you can flash the fuel into vapor in the lines. Vapor lock is fuel boiling."
Lastly, since fussing with the CDI connector yielded good results, visit that component again when the engine refuses to start.
Good luck and let us know what Gremlin caused the problem once you've gotten it resolved.
Chris Toy
356-930 Gone
Old 09-25-2009, 07:46 PM
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