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No start - checked usual suspects..grr!

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  • No start - checked usual suspects..grr!

    Hi guys

    Have a no-start problem on my S14B23. Car started about 3 months ago - hasn't been driven since then, but has fresh fuel and nothing else has been touched.

    Fuel pressure is spot on (40odd psi - running with fuel gauge inline with fuel line so I can monitor it as its running - gets up to around 45psi when cranking so no fuel related problem.

    Spark - all plugs are sparking with a good blue spark - earthed on rocker cover - all firing in order also - put all 4 spark plugs on rocker cover and cranked (minus fuel of course!) - all fired in order with good blue s park.

    PROBLEM: no start! Cranks easily and seems to catch but doesn't start - sounds like there is either no spark/fuel but as I have both only problem can be is lack of air / too much air - or something electrical.

    Compression is relatively even across all cylinders and within spec. Checked compression yesterday, dont remember numbers now but they were all ok.

    Only problem I can see at the moment: when cranking, vacuum gauge connected to vacuum line from intake manifold to fuel pressure regulator never goes below about 5 usually closer to zero. SO seems to me like very large intake air/vacuum leak - only problem is I have checked all the pipes in the intake manifold area that carry air and they are all good (even put them in water and blew through them to see any cracks - nope!)

    I will continue to try and find the vacuum leak or cure for the low vacuum - in the meantime anyone else have any ideas?

    In terms of electrical, I'm thinking the flywheel reference sensor could be the problem? Does anyone have the figures handy for resistance etc for testing the sensor?

    Cheers

  • #2
    Sounds really familiar to me, had the same problem and turned out to be one of the sensors at the flywheel. They have the same part no. anyway so just buy one and replace one at a time til it starts. good luck.
    Godspeed,
    John A.
    "If your ship doesnt come in, swim to it..."

    M3 e30 2.5L | R8 v8 6mt | 996 GT3 mk1 | Integrale Evo Martini 6 | Dallara F303/4 Toms | Defender 90 NAS

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    • #3
      I left my car sitting for a couple of months and it turned out the fuel injectors stopped firing. Took them out, tapped them on the ground, re-installed and car started.

      This also happened to another friend of mine. Such is the life of track cars that move every so often.


      Nick

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      • #4
        Thanks guys

        Thanks for the quick responses - I will try both the flywheel sensors and the injectors and let you know.

        I'm certain its not the injectors however as there is plenty of fuel smell coming from the exhaust on start up and the plugs were a little wet - before I dried them

        I'm thinking everything leads to the flywheel sensors although the lack of vacuum is still causing me concern.

        What figures should the flywheel sensors show (resistance etc) if I test them with a DVM? Does anyone have these figures handy?

        :chug:

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        • #5
          By the way - if I'm getting spark at each of the plugs and it's firing in order then isn't it more likely than not that the flywheel reference sensors are working? I would have thought that if the sensors weren't working there would be no spark at all?

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          • #6
            Yes, I don't belieev you'd be getting spark if the crank sensors are bad...and I've always had trouble believing crank sensors go bad just when sitting.

            Were all the plugs wet with fuel when you checked them?


            Nick

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            • #7
              On mine, I was getting spark and fuel pump was working, I maybe wrong but I think the injectors wont supply fuel if the flywheel sensor is broken. I replaced one of them then its all fixed.
              Godspeed,
              John A.
              "If your ship doesnt come in, swim to it..."

              M3 e30 2.5L | R8 v8 6mt | 996 GT3 mk1 | Integrale Evo Martini 6 | Dallara F303/4 Toms | Defender 90 NAS

              Comment


              • #8
                Thanks for all the responses guys, will check over the weekend and let you know how it goes. I'm definitely getting spark and fuel - plugs were wet (now dry!! ) so the only thing left is a vacuum leak, lack of air or something electrical.

                I haven't tried the ICV as yet - I spose I could have the dreaded ICV frying the ECU thing happened - which would explain both the lack of air and the electrical problem.

                I will test the ICV to see if its working - something tells me its not. Last time I had the car running before shut down (after a big of a long drive) the idle was about 1200rpm even with the idle screw almost all the way in. Seems like that dam ICV will be the next thing to check.....

                :shit:

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