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Start problem 1973.5 CIS
Hallo ,
Trying to start a restored 911T 1973.5 I try to check the pressures of the CIS system This car is equiped with a trottle valve 911 110 916 00. Mesuring the systempressure I found 3 bar. Where the BOSCH manual says around 4,8 bar???? Looking for a reason I disconnected the trottlevalve feedline. And now I mesured the 4,8 bar ???? Now I am twisted a bit  .By trying to start the engine I got a lot of backflash. Lucky there is a pop up valve?? Can somebody help mewith solving this ?? Thanks a lot Richard |
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03-03-2022, 01:38 PM
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System Pressure..........
Quote:
Richard, Could you post a picture how your measured the system pressure? Just want to make sure we are on the same page. Thanks. Tony |
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03-03-2022, 02:27 PM
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Hallo Tony,
Nice to read you. The pressure gauge is installed in the fuelline from FD to WUR. What is the function of the trottle valve 911 110 916 00? Why do I mesure,when this valve is operation,only 3 bar system pressure? I attach a photo. Thanks for your help Richard |
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03-03-2022, 10:19 PM
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Tony,
Second trail to upload photo Richard |
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03-03-2022, 10:30 PM
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Richard,
If you are having problem posting the picture/s, send the picture to ATD911@hotmail.com and will review your set up. Thanks. Tony |
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03-04-2022, 04:54 AM
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Hers a pic from the CIS manual. It has a cam inside with 3 positions to control the mixture at idle, part throttle, and full throttle. Later cars replaced it with a vacuum WUR.
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Ed 1973.5 T |
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03-05-2022, 05:18 AM
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Thanks Ed.
The funktion is now very clear to me. Can J install a new WUR,without vacuum? In case the existing is not working correctly anymore? I also detect that the trottle micro switch remain closed only in the few first millimeters and then iopens the switch ?????? This means if I pull the trottle handle full to the stop ,this switch is open and the cold start injector does not get fuel????? What can I do? Thanks Ricardo |
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03-12-2022, 02:23 AM
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It is the opposite. The micro switch should be open with the hand throttle down, and close completing connection as the throttle switch opens or gas pedal is pressed down. The start valve would then be activated when the ignition is in the start position and starter is spinning.
From my reading the wur can be replaced with a vacuum assisted one to eliminate the throttle position regulator. I have not installed it at this point in time, but I bought the replacement wur for the future. Rarlyl8 and Boyt911sc should be able to help you out. Here are some threads on the subject. WUR wiring single ended? 73.5 CIS Time to retire the 001 WUR
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Ed 1973.5 T |
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03-12-2022, 04:54 AM
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Good morning,
Ed I was able to change the switchconnections. Original the switch was connected between 11 and 12 . And now I found a third connection 14. I checked the links and found that the connection between 11 and 14 gives the closed connection when trottle handle ispulled up. Thanks folks for your help. The car is now starting much easier. |
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03-21-2022, 08:20 AM
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Good to hear.
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Ed 1973.5 T |
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03-21-2022, 04:14 PM
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The Other Woman
