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  #1  
Old 04-02-2009, 11:30 AM
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IP Shut off operation Question

Quick question regarding the IP shut off. My 84 300d will shut off but will then will run poorly and start hard if I attemp a restart shortly after I shut down. I was able to correct the problem by removing the vacuum at the IP shut off valve and releasing the vacuum (seems the shut off valve is remaining paritally engaged even after the car is started do to the presence of vacuum). I suspect the vacuum switch at the ignition is the problem but I am trying to understand the operation.

Looking at the vacuum diagrams the switch APPLIES vacuum to the IP shut off valve when you turn the Key to the OFF position. What is not clear is when the vacuum is RELEASED (to allow starting and normal operation).

Any thoughts?

Thanks,

Bob

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Old 04-02-2009, 11:56 AM
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I would suspect the ignition vac switch too.
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Old 04-02-2009, 12:01 PM
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At what point "should" the vac switch release the vacuum (i.e. as I turn the key?)
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Old 04-02-2009, 12:31 PM
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With in 5 or 10 seconds the vac to the shut-off valve on the IP should bleed off. If then the vac switch on the ignition is bad.
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Old 04-02-2009, 02:20 PM
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My CD shuts off instantly, the SD after a few seconds.
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Old 04-02-2009, 02:38 PM
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should be fairly easy to test with a mity-vac. Disconnect the vacuum supply line, usually brown, heading to the ignition switch and pump the mity vac up to 15 or so. Turn the key off with engine running and watch the guage. You'll probably have to provide some extra vacuum to achieve shut-off.
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  #7  
Old 04-02-2009, 03:14 PM
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Thanks for the input. I will post a follow up after I change out the Vacuum Valve on Saturday.
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  #8  
Old 04-02-2009, 03:41 PM
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Check for crud inside the vacuum lines to the shutoff valve. You may have to take the ignition switch apart to check things out in there, that is what im leaning on.
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Old 04-02-2009, 06:18 PM
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Your vac. pump may be getting bad. What I have seen happen is the shut off valve in the ip gets filled with oil and dampens the plunger in the ip .Look for oil in the lines.

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