Sudden high idle, rough idle, gas smell, very poor mileage

Discussion in 'General Motoring' started by Richard, Jan 13, 2004.

  1. Richard

    Richard Guest

    1985 Accord. 172k miles. Carburetor. Manual transmission.
    Air cleaner recently disturbed to explore occasional carb icing problem.

    Engine has been running well. **Suddenly** I have a high idle problem. Near
    the end of a 20 mile drive on a recent cold day, stopped at a light,
    suddenly the engine wouldn't idle down. Idling at 2K or more. I let out the
    clutch and the car almost drives itself - little accelerator required. I've
    not seen idle below 1.5K since. Runs rough, gas smell, and gas consumption
    is off the charts. On cold start, idle immediately jumps to 2.5K or more
    before idling back to about 1.5K. Fast deceleration or sharp left turn (!)
    seems to cause idle fluctuation.


    Richard D.
    Richard, Jan 13, 2004
  2. Sounds like a vacuum leak to me. Recheck your hoses or perhaps one of your
    hoses was hard and brittle and when moved it cracked.

    CaptainKrunch, Jan 13, 2004
  3. Richard

    Tegger® Guest

    Is there gas coming out of the float bowl vents? Sounds like a float that
    has sunk.

    Pull the air cleaner cover & peek inside the carb with the engine running.

    How much corrosion is there on the wiring in the engine compartment?
    Tegger®, Jan 13, 2004
  4. Richard

    Andrew Smit Guest

    you can first try to turn the idle down, there should be a knob on the
    back of the carb towards the passenger side, i believe that counter
    clockwise will turn the idle down. there may still be a vaccume leak in
    which case this bay only be a temporary fix
    Andrew Smit, Jan 13, 2004
  5. Richard

    Richard Guest

    Thanks Cap'n.. I'm a newbie, so please forgive the ignorance I'm about to

    I just sprayed for vacuum leaks. There is a small "black box" attached to
    the rear of the air cleaner. The only idle drop I hear is when I spray
    around that box. What is it? Should it be replaced? Is this my problem?

    I've also heard that EGR or PCV valves might be culprits. Is that consistent
    with the sudden onset of this problem? What do these valves look like and
    where are they?

    Richard D.
    Richard, Jan 13, 2004
  6. Richard

    Richard Guest

    Thanks, Tegger.

    Is sunken float consistent with the sudden onset of the problem?

    Please forgive my ignorance. When peeking inside the carb, what should I
    look for?

    I think wiring looks pretty good.

    Richard, Jan 13, 2004
  7. Richard

    Richard Guest

    An update:

    Engine also diesels (run on) for a few moments after shutdown. Never seen
    that in cold weather before.

    Light colored smoke for a few moments on startup in cool/cold weather has
    been an issue for a couple of years. Since the high idle began, there is
    much more smoke for much longer time (several minutes).

    While out driving this morning there was an interval of several miles where
    idle dropped and the engine stalled several times. High idle soon returned.

    Thanks for any available insight!
    Richard D.
    Richard, Jan 13, 2004
  8. Richard

    Tegger® Guest

    "Sudden onset"? I don't know. Maybe not. Seems to me a leaking float would
    gradually cause problems.

    There *is* another possibility I just thought of: The choke plate.

    With the engine fully-warm, the choke plate should be fully open, standing
    vertically. Is it? The choke plate is at the very top of the carb, covering
    the throat.

    With the engine idling, fuel dancing on the throttle plate. The bowl vent
    tubes are right up at the top, probably on a 45 degree angle, and with
    their ends cut off so they are flat to the horizon. If they are dribbling
    fuel, this will be very obvious.

    Is there a float bowl window on the side of this carb? That would settle
    the float level thing without any disassembly.
    Tegger®, Jan 14, 2004
  9. Richard

    Richard Guest

    Thanks to all who responded. I've decided to replace this relic. Know anyone
    who might want it?

    Richard D.
    Richard, Jan 18, 2004
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