Thread: Vapor lock
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TDH888 TDH888 is offline
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Join Date: Jul 2009
Posts: 131
Originally Posted by 356-930 View Post
"My mechanic & I are debating because I told him that the TTS when the engine is hot the TTS does not turn on the CSV." True, provided the TTS is working right.
". . . how come when the CSV is connected and he tries to the start the engine when the car has been shut down 30 mins after is having difficulty starting but when he disconnects the CSV the car starts immediately." Because the CSV is getting turned on when the engine is hot and it's not supposed to get turned on.
"The car simply refuses to start when its flooded. But when the CSV is immediately disconnected the car will sputter probably bec. of the flooding then it will settle to a nice idle." Remove extra fuel source (via CSV) engine starts. Sure sign of excess fuel.

The CSV is not supposed to be spraying fuel when the engine is hot. (Smelling raw fuel, unplugging it, getting the engine to start without it plugged in is a sure sign the CSV is adding fuel when it should not).
If the CSV is spraying fuel when attempting to start the engine when it is hot, either the TTS is bad or the lead from the TTS to the CSV (or the CSV itself) is shorted to ground. Again, the CSV is supposed to add fuel only when the engine is cold.
I don't have a wiring diagram but here's how it works. You can trouble shoot with a volt meter. There is an auxiliary terminal on the starter motor that gets 12V applied to it only when the starter motor is engaged. The "hot side" of the TTS and one side of the CSV are tied to this terminal/to each other, i.e. they are common. The second terminal of the TTS is grounded (when cold) and is wired to the second terminal of the CSV. When the starter motor's auxiliary 12V terminal gets turned on, (during cranking only) the CSV flows fuel as long as the TTS’s ground lug remains grounded, 10-seconds or less when cold. The lug should not be at ground when the engine is hot. It should not be at ground after extended period of cranking.
Make sure that 12V is Not present on the TTS or the CSV when the ignition is “on.” The TTS should see 12V only when cranking.
Now, disclaimer. This is how a ’79 930 CIS fuel/start system works. Perhaps as Pat Keefe notes, your model/year could be different?
You must be getting fuel pressure of some measure or no fuel smell when hot.
And do get a CIS fuel control pressure gage set. No more guessing at some of these fueling problems.
Thanks Patrick & Chris will suggest this to my mechanic.
Old 09-27-2009, 05:47 AM
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