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Hard to start VS V8

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by vombil, Jun 13, 2018.

  1. vombil

    vombil Member

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    I have a 97 VS V8 which takes 2-3 turns of the key to fire when stone cold. No problem starting warm and drives perfectly once it's running.
    I've cleaned the throttle body and IAC and also put a different ECU in it.
    Interestingly you cannot hear the fuel pump priming when you turn the ignition.

    I know it's a long shot but any takers? My gut tells me there's an issue with auto choke or TPS or something in the throttle body. It was 'hunting' too prior to me cleaning the throttle body.
    I've had a commy give starting issues when it had fouled plugs. I suppose I should check them but yeah, it does not miss when it's running so I didn't bother looking.

    TIA
     
  2. VS 5.0

    VS 5.0 Well-Known Member

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    Is this with every attemped start, whether hot or cold, or only when it won't start.

    When it won't start, is it cranking and not firing or nothing at all ?
     
  3. someguy360

    someguy360 Well-Known Member

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    If your not hearing the pump prime, I suspect you probably have an intermittently faulty pump, maybe it's triggered by sitting for long periods.
     
  4. immortality

    immortality Moderator Staff Member

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    Check the fuel pump relay.

    The fuel pump is supplied power via the oil pressure switch, this is a safety feature in case of an accident so when the engine shuts off/stalls the fuel pump stops. For the VS the fuel pump relay is a 2 way relay. In it's normal off position the relay supplies power to the pump via the oil pressure switch, when you first turn on the ignition the PCM will energise the relay and power the pump bypassing the oil pressure switch. See the attached wiring diagram.
     

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  5. BlackVXGTS

    BlackVXGTS Well-Known Member

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  6. lowandslow

    lowandslow Well-Known Member

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    My VQ 5L would take ages to start when cold 95% of the time. Was a dud ecu temp sender. (there are 2 next to each other under the TB)
     
  7. vombil

    vombil Member

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    yeah i think this is worth looking at. i might pull the fuel line off and hit ignition. that should tell me pretty quickly
     
  8. vombil

    vombil Member

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    yeah a mate of mine suggested this might be the case. will looking into it
     
  9. vombil

    vombil Member

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    checked plugs today and they are all very clean and look fairly new. bit moist like over fueling but not dirty. no codes at all!
     
  10. vombil

    vombil Member

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    only issue on first start mate then it's OK for the rest of the day. next morning when stone cold its a pig. cranks and has spark just won't run. im not sitting there cranking the hell out of it. should fire immediately, if not then i turn key back and hit it again for a couple seconds. second or third key stroke and it's running nicely.
    it used to hunt and stall and **** before I cleaned IAC and throttle. it goes like a cut snake. one of those freak motors. no cam, no diff gears, no exhaust. just a freakish donk. it would chew up any stock roller motor 5L i've ever owned
     
  11. vombil

    vombil Member

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    i've had this happen with a VS v6 ute now i think of it! was a **** box to start but when running, it was fine. I drove that ute to my mates place and first thing he checked was pressure by removing the line and hitting the key... pissy little dribble of fuel fell out. changed it out and cold starts were not a problem after that
     
  12. BlackVXGTS

    BlackVXGTS Well-Known Member

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    Note well.
    • The Holden 5l has a coolant temperature sender (two wire) that runs the temperature gauge.
    • It has a coolant temperature sensor (CTS) (three wire) that provides the ECU/PCM/ECM with input to modify various levels of engine performance/radiator fan control and other items such as transmission performance in the case of a PCM (auto).
    There are no reasons to replace the sender unless you are having problem with the temperature displayed on the gauge.
     
  13. lowandslow

    lowandslow Well-Known Member

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    Or the sender to ecu is cactus and it's telling the ecu the engine is too hot and it tries to dump fuel in to cool it down.
     
  14. vombil

    vombil Member

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    plugs do look like it's over fueling a little. not nice and dry. colour is good though and not carbon polluted or lean. i pulled the fuel supply line off at the firewall and hit the ignition. fuel does not spray out to the front bumper as I've seen in other VS cars ive tried it in. i'll try on another one of my v8 utes and compare the pair! I've got a feeling it's a weak pump
     
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  15. losh1971

    losh1971 Well-Known Member

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    Might need a new fuel filter. Best try that first.
     
  16. vombil

    vombil Member

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    filter looks new. took it off and it's all OK so refit it. Interestingly, i hit the key a few times in a row and the pressure left the building. ended up just being a dribble! so i went over to my vs v6 (runs perfectly) and took the same line off and... bang... no fuel came out at all! that ute runs like a dream. FML :/
     
  17. immortality

    immortality Moderator Staff Member

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    I made up a little test wire and bypassed the ignition. I simply removed the relay and hotwired from the battery to turn on the pump and test flow. Since then I got one of these Power Probe 3 which allows you to test for voltage but also either ground a circuit or apply 12 volts to activate circuits. Has a really long lead so you can connect it to the battery and work at the back of the car.

    Turning on the ignition only primes the fuel system for a couple of seconds so its not really a good test for flow/pressure.
     
  18. vombil

    vombil Member

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    ok mate that makes sense then. my mate suggested that was a good test! another buddy has one of the those tester things you're talking about. think im going to borrow that!
     
  19. vombil

    vombil Member

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    Update - I've changed the fuel pump and absolutely no change. Infact it ran like an absolute pile of **** and would barely idle. Once it was warm it was like a cut snake again. It's a real weapon! I don't know if it's getting too much fuel (based on the look of the plugs) or too little. Either way it's really bugging me. I hate spending time fault finding and thinking of calling in the big gun...
     
  20. lowandslow

    lowandslow Well-Known Member

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    *sits in corner looking at the coolant sensor*
     

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