Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16

Thread: Advice sought: '71T not starting

  1. #11
    Another update on my end: I was able to see fuel squirting into the carburetor. The attached photo is a screen grab from a video captured on my cell phone. That drop of fuel you can barely see was a welcome sight!

    So was all this operator -- me -- error? Not correctly doing the most basic starting procedure? If so, I mark that down as a stark reminder of my tremendously low starting point for knowing my car and an indication of how much I have to learn. I'll also be glad that no repairs are needed.

    I enjoy learning about these precious cars. They are an extraordinary engineering, design and business (i.e., packing all that engineering and design into a price point that many people can access) feat even 50+ years later.

    Thanks for everybody's assistance, especially Ed and Paul.

    HowardName:  IMG_2060.jpg
Views: 173
Size:  35.9 KB
    1971 911 T Targa, metallic green

  2. #12
    You may not be getting as much fuel discharge from the accelerator pumps as you should, which can sure lead to your starting problems. There is a specific measurement of amount, but suffice it to say it would be a definite stream, not just a dribble. That will need to corrected but for now it means you may have to pump the throttle maybe a half dozen times BEFORE cranking in order to get sufficient fuel down in the cylinders to enable running. This would be the part where if no one available locally, you send the carbs off to Paul.
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.

  3. #13
    As Ed said, squirter output should be a stream and not a drop. There is a prescribed amount of discharge volume per nozzle per one full stroke of the throttle lever arm. Since there is no "choke" on our carbs for cold starting we must rely upon the squirt from the accelerator circuit to richen the mixture for starting and for keeping the engine running until a steady idle is established.

    A rebuild may be in order to diagnose the issue which is most likely the check valves in the squirter nozzles or in the inlet valves in the bottoms of the float bowls being stuck which will inhibit the accelerator pump to fill with fuel.

    I am no longer servicing the Zeniths but have transferred my knowledge to David Cheney. His phone number is: 651.785.8792 His web site is: https://www.dccarburetorrestoration.com/
    Paul Abbott
    Early S Member #18
    Weber service specialist
    www.PerformanceOriented.com
    info@PerformanceOriented.com
    530.520.5816

  4. #14
    Final (probably) update on my end: I got the car started and was very careful to not crank the engine until after pumping the throttle several times. "Many" might be more accurate than "several". I pumped it half a dozen times and then cranked; the car would sputter for a moment then the starter would strain to make something happen. After about 10 seconds of straining with no improvement to the sound of things (i.e., I got no sense that anything was "catching"), I would turn the key to the off position. I repeated the process, but the next time pumped the throttle 8 times. The car would sputter for a bit longer than the first time, but ultimately would reach the same outcome (straining starter with no sense of anything catching). I repeated the process, each time getting a bit more life. Eventually the car started and sustained idle. Note that the garage was about 45 degrees F and by now the car hadn't run for about a month.

    Phew!

    The "too little fuel" diagnosis sounds right. I need to re-think my next steps with the car in light of this development (I hadn't planned to focus on the carbs at the moment, but realize that one can't always control these things). From other posts each of you have made (and Paul's web site), I know that Ed is a "believer" in Zeniths and Paul not much so. Given that Zeniths have been on my car from its beginning (and Ed's endorsement of them), I'll try to make them work. I'll reach out to David Cheney as a prospective partner in my long-term journey with this car. I'll do that after getting a few other details sorted out before shutting the car down for the winter.

    I've enjoyed learning about the car through this episode. My wife is not at all surprised that there was an element of operator error (me) involved!

    Thanks again for being so generous with your expertise. Much appreciated. Howard
    1971 911 T Targa, metallic green

  5. #15
    Well true it is that I'm not a lover of Zeniths except for OEM installations. Upping engine performance with Zeniths is not an easy task, this is my reluctance for embracing Zeniths.

    I think you have discovered that your accelerator system is in need of sorting out. Cold starting requires some blipping of the throttles to richen mixture and this can only be done if the squirters are actually squirting an appropriate amount of fuel.

    When cold started, the fuel will not combust very well which results in a "lean" condition although the mixture will be good once the engine warms. Spitting up through the intakes is typical after a cold start. Once combustion chambers warm up a little, atomization/vaporization is much improved and the mixture will be more fully developed which will then create a more combustible mixture. I see this when starting my test engine, AFR will be in the 17s and after about one minute the AFR will be 11.5, this is without adjusting any setting on the carb.
    Paul Abbott
    Early S Member #18
    Weber service specialist
    www.PerformanceOriented.com
    info@PerformanceOriented.com
    530.520.5816

  6. #16
    Senior Member Haasman's Avatar
    Join Date
    Apr 2011
    Location
    N.Calif., south of SF
    Posts
    1,965
    Paul, thanks for this. Very interesting and helpful.

    When cold started, the fuel will not combust very well which results in a "lean" condition although the mixture will be good once the engine warms. Spitting up through the intakes is typical after a cold start. Once combustion chambers warm up a little, atomization/vaporization is much improved and the mixture will be more fully developed which will then create a more combustible mixture. I see this when starting my test engine, AFR will be in the 17s and after about one minute the AFR will be 11.5, this is without adjusting any setting on the carb.
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

Posting Permissions

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

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.