Air/Fuel Mixture adjustment

Discussion in 'General Motoring' started by MC, Oct 31, 2003.

  1. MC

    MC Guest

    Ok, I took out the carburetor ('87 Honda Accord LX) and put in a new kit
    (gaskets, o-rings). I also replaced almost every hose I could lay my hands
    on. The ones I couldn't replace and that were in good condition I also
    clamped the connecting ends.

    Now:

    1) Engine still stays up in the 2500-2900 rpm (connected tachometer, the
    dash tachometer is about 300-400 rpm higher). My manual (Helm) says to
    check the dashpot system if the warm idle rpm is too high. There is vacuum
    on hose #6 (the one connecting to the throttle controller) and you can also
    see the rod from the throttle controller moving when you connect the hose.
    The next cause can be air/fuel mixture adjustment. Here the manuals says to
    check the dashpot system first (which I did) and that the warm idle rpm
    should be 800 +-50. But as you can see my car's rpm is too high. Should I
    go ahead and adjust the air/fuel mixture starting at that high rpm?

    2) Both the manual and the carb kit instructions say to remove the mixture
    adjustment screw cap and leave it removed in order to perform the air/fuel
    mixture adjustment. The thing is that I had to remove so much stuff to get
    that carburetor out (hoses, idle boost throttle controller, etc, etc). The
    maze of hoses and metal tubes between the carburetor and the firewall make
    this a non-trivial task!!! After I adjust the air/fuel mixture, is it
    really necessary to put the cap back in...? Or can I do without it (so that
    I don't have to remove all that stuff again... :(

    3) I tested the secondary diaphragm (to the right of the throttle
    controller, in front of the carburetor) and the rod moves when you appply
    vacuum and the vacuum holds. However the rod doesn't move that much... just
    enough for you to notice that the diaphragm is responding to the applied
    vacuum. Is this normal for this type of test?

    4) THREE adjusting screws!!!! The throttle stop screw (back of carburator
    facing the firewall; has a plastic knob) is a pain to get to, but wait!...
    the fast idle adjustment screw is almost impossible to get to......(below
    the throttle adjustment screw) Which one should I fiddle with first to get
    the idle speed down to what is should be? Also, on the throttle stop screw,
    increasing rpm is clockwise our counterclockwise? Right now the engine
    doesn't seem to respond to major movements (1 complete turn either way) on
    the throttle stop screw. It just stays high. Or maybe I'm just way way out
    of speck and need to keep moving the throttle stop screw until there is a
    noticeable difference in rpm? But again, which way is up?

    5) I continue to look around for disconnected hoses or hoses that don't look
    too good in order to replace them... I haven't been able to find any vacuum
    leaks (yet).

    Please help!

    MC
     
    MC, Oct 31, 2003
    #1
  2. MC

    N.E.Ohio Bob Guest

    You could try a can of carb cleaner. With the engine running, spray all
    the places you think could be leaking. If the carb cleaner goes in a
    leaking spot, the engine will slow or stop. bob
     
    N.E.Ohio Bob, Oct 31, 2003
    #2
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