Results 1 to 7 of 7

Thread: 1971 Engine compartment wiring question

  1. 12-13-2020, 01:23 PM #1
    alberta
    alberta is offline
    Member
    Join Date
    Jan 2018
    Posts
    83

    1971 Engine compartment wiring question

    My question is I have 3 plugs that I'm not sure where they go. My car is a 1971 911T with carbs. The larger plug appears to be a rear fog light plug.
    The other two plugs with red and white wires have me stumped. There is also another electrical plug ( red and white wiring) that runs off the same wire harness as the two in the picture that ends under the air cleaner area and connects to nothing.
    Any help would be appreciated. Everything appears to work although I have not tried the rear defrost.
    Thanks John
    Attached Images Attached Images   
    Reply With Quote Reply With Quote
  2. 12-13-2020, 05:45 PM #2
    Richy
    Richy is offline
    Senior Member
    Join Date
    Oct 2010
    Location
    Southern Ca.
    Posts
    1,181
    I believe the large plug is for a rear fog light . The two plugs together go to a microswitch activated by the the throttle cross bar lever . The other plug connects to a solenoid to close the idle circuit on the carburetors . Part of the emissions deceleration system
    Reply With Quote Reply With Quote
  3. 12-13-2020, 10:00 PM #3
    timmy2
    timmy2 is offline
    Member
    Join Date
    Apr 2013
    Posts
    88
    Large plug with blue/yellow and brown/white wire is for Sportomatic option.
    Other wires are for limit switches and cold start devices on MFI engines.
    Porsche used one basic harness allowing different options for all cars.
    Reply With Quote Reply With Quote
  4. 12-14-2020, 05:10 PM #4
    Richy
    Richy is offline
    Senior Member
    Join Date
    Oct 2010
    Location
    Southern Ca.
    Posts
    1,181
    The wires are not for limit switches or cold start , but for the deceleration anti-backfire system , which '71's with carburetors had .
    Reply With Quote Reply With Quote
  5. 12-14-2020, 07:54 PM #5
    alberta
    alberta is offline
    Member
    Join Date
    Jan 2018
    Posts
    83
    Thanks guys for the reply. I would agree with Richy, my car has Webers but would have had Zenith carbs. Its a matching number 911T. After researching 911T microswitch I found this picture on Pelican, which shows the wire going to a microswitch for Zenith carbs. Mystery solved!
    Name: DSC008251108433860.jpg Views: 284 Size: 59.7 KB
    Not sure how this switch works but I read it was problematic.
    Thanks John
    Reply With Quote Reply With Quote
  6. 12-15-2020, 12:08 PM #6
    samll
    samll is offline
    Junior Member
    Join Date
    Nov 2020
    Posts
    1
    Thanks guys for the reply. I would agree with Richy, my car has Webers but would have had Zenith carbs. Make sure to visit Loanwinners for some info on the best US lenders Its a matching number 911T. After researching 911T microswitch I found this picture on Pelican, which shows the wire going to a microswitch for Zenith carbs. Mystery solved!

    Not sure how this switch works but I read it was problematic.
    Thanks John

    not all the mystery solved, one question remains
    where is your microswitch and how did it get loose!
    Last edited by samll; 01-20-2021 at 05:36 AM.
    Reply With Quote Reply With Quote
  7. 12-16-2020, 08:45 PM #7
    targatuesday
    targatuesday is offline
    Senior Member
    Join Date
    May 2019
    Location
    Sunny Scottsdale, Arizona
    Posts
    107
    Quote Originally Posted by samll View Post
    not all the mystery solved, one question remains
    where is your microswitch and how did it get loose
    It would have been removed when the Zenith carbs were replaced with Webers. The micro switch only works with the system built onto the Zeniths.
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules


Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.