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Thread: 4ac pre-ignition

  1. #1
    Member Aezion's Avatar
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    Default 4ac pre-ignition

    The story
    The old 4ac died so i did a swap for a reco'd one that came with an electronic dizzy, everything is wired up and running i even went and got a new radiator


    The problem
    when i turn the car off the engine the car wants to keep going. its getting to the point where i have to stall my car on purpose just to get the engine to stop


    i did the tappets they're fine, timing light said it was fine, i ran a bottle of carby cleaner through with a full tank of unleaded.

    what is the problem? spark plugs? ignition leads? carby settings?
    any help would be much appreciated. because im outta ideas

  2. #2
    Veteran biggo's Avatar
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    Default

    Your fuel is igniting on its own. Usually caused by burnt carbon that red hot.

    Try some carby settings, 98 ron fuel and check the timing again.

    Maybe pull the electrionic dizzy out and swap it for a normal one?

  3. #3
    Senior Member Dylan's Avatar
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    mine used to do this. Was just a little too much advanced

  4. #4
    Veteran Jonny Rochester's Avatar
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    It is a broken O-ring on the fuel cut-off switch, or "anti-deiseling" switch.

    Look for a 12v ignition wire going to the carby. One of these wires goes to a solenoid on the carby. Turn the ignition on and off and you will hear it click. Unscrew it with a 12mm spanner, and look at the tiny O-ring on the end of it. You need a new one.

    The broken O-ring is letting fuel pass by it even when it is turned off.

  5. #5
    Member Aezion's Avatar
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    do i need to buy genuine toyota solenoid or can i get one that will fit from the wreckers?

  6. #6

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    Mine wasn't working either.. I took it to my carby guy and he had a spare part for it lying around so I don't think it'd need to be genuine toyota.

  7. #7
    Veteran Jonny Rochester's Avatar
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    Most often the solenoid will work if the 1 wire is connected to ignition. The common problem is the mini o ring needs to be replaced.

    As said, fairly easy to find another off a different carby.

  8. #8
    Member Aezion's Avatar
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    cheers guys ill have play around with it and see how i go

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