Strange start problem...is my logic okay?

Discussion in 'General Motoring' started by Jim Mowreader, Jul 16, 2006.

  1. I have a 1986 Accord LX-I with manual transmission.

    When the car is cold, it starts fine, and it always runs fine. It likes
    to idle at 2000rpm sometimes, but there's no hesitation or weirdness in
    its operation.

    When the car is warmed up, it will crank and crank and crank for quite
    some time before it starts...kinda like running out a flood on a car
    with a carburetor.

    A strange one: if you push-start the car when it's warm, it fires right
    up. But I totally trashed the left inner CV--tearing a hole in the oil
    pan in the process--when I did that once, so no more of that.

    So I thought, if I pull the fuel pump fuse and crank the engine, maybe
    it will start. Pull the fuse, the car runs for about three
    seconds...which is all you'd expect to get. Stick the fuse back in, car
    sometimes starts and sometimes does not. But you do the fuse in-out
    thing, and eventually the car starts.

    As an experiment, I bought a 30-amp automotive switch from RadioShack
    and wired it into the fuel pump fuse circuit. This works pretty
    well...if you turn the fuel pump on, crank the car for a few seconds,
    then turn the fuel pump off, it fires. Immediately start pumping the gas
    and turning the pump on and off, and within 20 seconds the car will be
    running. And like I said, once it is running it runs great.

    I think my coolant-temperature sensor (aka "thermowax sensor") is
    screwed up, always reporting that the engine is cold. This device
    probably only gets read at startup--if the engine's cold, dump more gas
    in and it will fire right up; if you dump more gas in when it's hot the
    engine floods. I'm thinkin' the mixture-enrichment cycle only lasts
    about ten to fifteen seconds because once I'm out of that period, the
    engine runs stably in a very short period of time.

    I've already changed the fuel injector seals, and they needed it. I
    changed the thermostat because the car liked to overheat, and that also
    seemed to make it start a little easier. Would it be good to start
    hitting junkyards looking for a new thermowax sensor? I know the dealer
    price on one will be astronomical.

    --jm
     
    Jim Mowreader, Jul 16, 2006
    #1
  2. Jim Mowreader

    jim beam Guest

    google this group for the #1 most common failure in older hondas,
    especially in summer. 30 seconds research would have saved you a bunch
    of time and money.
     
    jim beam, Jul 17, 2006
    #2
  3. Jim Mowreader

    CCTGENE Guest

    When the car doesn't start are you getting spark? If so, then maybe the fuel
    pump relay.
     
    CCTGENE, Jul 17, 2006
    #3
  4. I looked at the relay issue before I wrote the OP and it really doesn't
    seem applicable.

    1) this happens all year round--not just during the summer.
    2) I just went outside and started the car. I got three clicks. When the
    car is dead cold, it always starts within a couple of seconds of turning
    the key to the "start" position--normally one second. (After I put the
    new injector seals in, it doesn't even need the two-second pause for the
    fuel pump to pressurize the rail--stick the key in and turn it straight
    to "start," it fires right up.)
    3) When the engine is hot, if you push-start the car (which doesn't
    activate the starter, hence doesn't tell the PGM-FI "you're going
    through a startup cycle") it always starts.
    4) When you start the car hot and turn off the fuel pump during
    cranking, it fires right up--naturally, it won't STAY running because no
    gas is being pumped, but it does start running. And when you sit there
    and feed it gas in little increments by turning the fuel pump on and off
    and pumping the gas so the engine will continue to turn, eventually it
    gets through that time when the PGM-FI wants to overdose the engine on
    gas and it runs.
    5) While this cranking and pumping thing is going on, there's a very
    strong smell of gas around the car, like a car with a carb gets when
    it's flooded.

    If it was a main relay problem the car wouldn't run at all, and the car
    runs fine. It's just a livin' bitch to start it when it's hot.

    --jm
     
    Jim Mowreader, Jul 17, 2006
    #4
  5. Jim Mowreader

    jim beam Guest

    main relay. but it's worse when hot.
    the seals have /nothing/ do do with ability to start. they just hold
    the gas in the rail and stop the engine sucking air, depending on which
    end of the injector you're looking at.
    er, it wouldn't run at all if the injector system couldn't figure out
    when to start injecting...
    ok, that's more diagnostic. do two things - check into flooded start
    conditions and remove plugs to see if you can find the wet one. that'll
    give you the leaking injector.
    unfortunately, the worst thing about the relay is that it's
    intermittent. i strongly recommend you repair or replace it as a
    precaution. the chances of this vehicle at this age /not/ being
    affected is slim to zero. then you have a clear run at your other
    symptoms without false positives.
     
    jim beam, Jul 17, 2006
    #5
  6. Jim Mowreader

    Jim Yanik Guest

    Indicating the car is not CRANKING. could be a starter problem.
    (solenoid contacts?? they can be replaced.)
    Could be a worn ignition switch;not energizing the starter.
    PGM-FI (ECU) does not monitor the starter.
    Not true.
    MR is the most problem when the car is hot,but once the car starts,it stays
    running,and always starts when cool.
    Does the car not crank,or cranks but doesn't start? (when hot)
     
    Jim Yanik, Jul 17, 2006
    #6
  7. Jim Mowreader

    Jim Yanik Guest

    Not true.
    Yes,it's SO easy to just resolder the relay and ELIMINATE it as a trouble
    source,and doesn't cost anything except a little time.

    Then he could look at starter problems,or whatever.
     
    Jim Yanik, Jul 17, 2006
    #7
  8. It gets spark.

    jm
     
    Jim Mowreader, Jul 17, 2006
    #8
  9. The car cranks fine. It runs fine once engine starts.
    It starts fine when cold.
    It needs to have the gas pedal pumped and pumped and pumped when
    starting hot.
    Once the gas pedal is pumped enough during a hot start to get it to run,
    the car runs fine.

    It's not an intermittent problem; it happens on every hot start.

    It gives the indication of flooding only during hot starts; once the
    car's running, it runs like nothing's wrong with it. It doesn't flood on
    cold starts.

    And this is the really weird part of the whole problem: once the car
    starts, it runs exactly as it should.

    I'm thinking this is the logic the car uses when a start command
    (turning the key to the "start" position) is issued:

    on (startup):
    if (start_switch) = "on" AND (coolant_temp) < 120 deg F
    then
    inject additional fuel quantity for 10 seconds
    and
    run starter
    end if

    or

    if (start_switch) = "on" AND (coolant_temp) >= 120 deg F
    then
    inject standard fuel quantity
    and
    run starter
    end if

    But for some reason, this particular specimen can't figure out that it's
    already warm, so it dumps more fuel into the engine than the engine can
    use, and floods it out.

    --jm
     
    Jim Mowreader, Jul 17, 2006
    #9
  10. Jim Mowreader

    Jim Yanik Guest

    shouldn't make any difference on a fuel-injected car;there's no
    "accelerator pump" to shoot more gas into the airstream.
    Or the main relay has cooled enough to work again.
    I don't believe that the change in fuel would be that significant,to flood
    it out.(At temps other than winter conditions)


    It's sounding more and more like the main relay.
    Your other post says you have spark.

    You say if you pushstart the car,it starts and runs.
    The ECU would not know that,the starting mixture would be the same as if
    you cranked it with the starter.
    If it -were- flooded,pushstarting it would be no different.


    Of course,removing and resoldering the relay is fairly easy and doesn't
    cost anything,and ELIMINATES it as a problem.
    You seem to be resisting this.
     
    Jim Yanik, Jul 18, 2006
    #10
  11. Jim Mowreader

    jim beam Guest

    yeah, that one had me do a double take as well!
     
    jim beam, Jul 18, 2006
    #11
  12. Jim Mowreader

    jim beam Guest

    dude, you don't "pump and pump" to hot start a potentially flooded
    engine. you press the pedal to the floor and keep it there while you
    crank. that tells the ecu to /not/ inject to clear a recognized
    no-start condition.
    that is an intermittent problem! exactly like a main relay.
    main relay.
    main relay.
    it's a little more complicated than that, but if you really want to
    know, look up the open source injector code for "megasquirt". "google
    ees yor frien'."
    dude, fix the main relay, then come back and tell us if if your problems
    persist.
     
    jim beam, Jul 18, 2006
    #12
  13. ---------------------------------

    It's the main relay. Chilling the interior, or vibrating the relay will
    make it work properly. That's why push starting it works. Smacking the
    dash on the left side with the key in position II will force it to prime
    the rail too, or slamming the door. .

    Just fix the relay. . . . Life is too short.

    'Curly'
     
    'Curly Q. Links', Jul 18, 2006
    #13
  14. Doesn't the crank position sensor (which would trigger during a push
    start, since the distributor is turning) tell the PGM-FI when to inject?

    --jm
     
    Jim Mowreader, Jul 18, 2006
    #14
  15. I got up under the dash and resoldered the relay late yesterday. (At
    this point I am thinking that the placement of this component is payback
    for the Chester Nimitz overseas-postage stamp...) Today I took the car
    to work.

    First start was at 4:30am. It started normally.
    Second start was at 2:15pm. (Yes, I work weird hours.) It started
    normally.

    So far it's working just like it did before I resoldered the relay.

    Third start, because I had to go home, pick up a bill and mail it, was
    at 2:30. Back to the ol' twenty-second pump-and-flip routine complete
    with gas smell.

    When I got home after my trip to the post office, I opened the hood and
    plugged/unplugged the coolant temperature sensor about ten times on the
    off chance that maybe the connection was just crudded up. It happens,
    right? I then got back in the car, turned the key...normal start. I ran
    it around some more, came back and shut down. I waited a minute and
    turned the key...normal start.

    I didn't want to resolder the relay because what this car is, or at
    least was, doing isn't like Tegger's description of what the relay does
    when it screws up. For instance, it always gave the three clicks it's
    supposed to. But it's resoldered.

    --jm
     
    Jim Mowreader, Jul 19, 2006
    #15
  16. I've tried that. It doesn't work. Press the pedal to the floor and keep
    it there, the thing revs for three or four seconds then dies. And you
    smell gas. Pump the shit out of it for 20 seconds and you're running.

    --jm
     
    Jim Mowreader, Jul 19, 2006
    #16
  17. I resoldered the relay and it didn't solve the problem.

    Cleaning the contacts on the coolant temperature sensor, by plugging and
    unplugging it a handful of times, solved the problem. It starts right up
    now.

    --jm
     
    Jim Mowreader, Jul 19, 2006
    #17
  18. Jim Mowreader

    jim beam Guest

    of course - you have to let the throttle back to a more normal position
    the moment it fires!!!
    there no injection programming to support this action.
     
    jim beam, Jul 20, 2006
    #18
  19. Jim Mowreader

    jim beam Guest

    let's get this back into context:

    you originally wrote:
    "3) When the engine is hot, if you push-start the car (which doesn't
    activate the starter, hence doesn't tell the PGM-FI "you're going
    through a startup cycle") it always starts."

    check out tegger's description of main relay operation - that'll explain
    everything for you.

    bottom line, if the main relay is operational, it'll start regardless.
    if it's got intermittent open circuit, the "start" position will not
    ground the injectors, hence the problem and the difference between the
    two modes. the ecu triggers the injection cycle when the distributor
    tells it to - regardless of how the crank gets to be rotated.
     
    jim beam, Jul 20, 2006
    #19
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.