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Thread: MFI Help needed

  1. #1

    MFI Help needed

    69 911 E Targa

    Car sat for 16 years in a shed before I bought it.

    Fuel tank was pulled, cleaned and relined.

    Fuel line was blown clear with brake cleaner before being hooked up again.

    New filter and soft FI lines installed.

    Car starts and runs but has a little poping on cyl #5 when it's cold.

    When it's warmed up it seems to run fine (once the needle moves on the dash gauge)

    Been driving it for 2 years (stored for the winters)

    While investigating the poping it was found that #5 is not getting fuel. It appears that it might be getting a bit of fuel but not enough to run properly.(swapped out the injectors and the injector is working fine).

    I've been reading threads from this collection all day looking for a simular problem but nothing found: http://forums.pelicanparts.com/porsc...ard-index.html

    Is it possible that one piston is stuck but when the engine warms up it moves enough to supply enough fuel?

    Any other thoughts on a cause?

    Pulling the hard line from the MFI unit to the #5 injector tomorrow to see what's up with it.

  2. #2
    Sure it is not too much air from worn throttle bodies?
    1971 911S, 2.7RS spec MFI engine, suspension mods, lightened
    Early 911S Registry Member #425

  3. #3
    The car only has 107,000 km on it (63,000 miles)

    What's the chance the TB's would be that worn?

  4. #4
    the piston lacking full movement is possible. probably worth pulling the pump to check. the piston pretty much has to reach the top of it's travel, due to the cam, but it may be hanging up and not dropping all the way down. I've gone through a number of pumps and this condition is fairly common.

    also there is adjustment under the injector line fitting, but I'm not real sure how to approach that. my gut feeling is to not start adjusting things before eliminating everything else.

    once you have the #5 injector line off, remove the injector and attach it to the end of the line with the injector in a container, connect pump end and turn over the engine. you'll be able to see the fuel spray. do this with another line and you can compare fuel spray and quantity.

  5. #5
    Quote Originally Posted by GWN7 View Post
    The car only has 107,000 km on it (63,000 miles)

    What's the chance the TB's would be that worn?
    Pretty much 100%.
    Tom F.
    Long Beach, CA

  6. #6
    Pulled the hard line. Ran air thru it. No blockage. Loosened the top of the pump and tightened it back down. Not sure what we did but it started to deliver fuel and is running fine.

    Who rebuilds TB's? Think I might just get them done over the winter to eliminate any future problems in that area.

  7. #7
    The name I think of first is Eurometrix. There is a list of MFI resources on the Early 911S Registry homepage: http://early911sregistry.org/Resource-MFI.html

    Also, there are a few threads by Jeff Higgins http://forums.pelicanparts.com/porsc...t-surgery.html on Pelican parts but here is the MFI Resource thread: http://forums.pelicanparts.com/porsc...ml#post2441556 and http://forums.pelicanparts.com/porsc...1st-draft.html
    1971 911S, 2.7RS spec MFI engine, suspension mods, lightened
    Early 911S Registry Member #425

  8. #8
    Grady over on Pelican is an MFI guru too and welcomes discussing MFI issues and has decades of knowledge. You might get his thoughts too
    Early 911S Registry #750
    1970 911E - The Good Stuff
    2001 Toyota Landcruiser

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