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Starting issues

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  • Starting issues

    I have been trying to start my engine today and it did run before i started work on it a few months ago however it ran badly. Now it won't even fire! I have checked fuel delivery, which is good, and i checked the spark between the wires which go from the distributor to the spark plugs. I checked the spark by putting a bolt in the wire and holding it about 1/8 away from the block. There is no spark at any of the wires. I then checked the distributor by taking off the cap and checking the spark there. It had a spark. My question is this. If there is a spark in the distributor, what could it be? The wires possibly?

    Any suggestions of what to do next would be helpful.

    Thanks in advance and sorry to keep asking questions.
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  • #2
    As always it is hard to give advice without actually putting our hands on the project in question, but I might could give you some ideas. If your distributor and coil is functioning properly as you say it is, I would check the rotor in the distributor. Sometimes they get a build up on the tip after sitting for a while. Lightly clean the rotor tip as well as the terminals inside the cap. Also check the top of the rotor where it contacts the carbon button for the coil wire. If it is not dirty, check to see if it is making contact with the carbon button in the cap and what condition the carbon button is in. I have had brand new cap and rotors that did not fit up correctly a couple of times.

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    • #3
      Sam, Post these over on the Calgary Volvo Club (www.calgaryvolvoclub.com). I can help you there and the rest of the locals will be a great help. Heck, they've been known to come over and assist. Let's keep this forum to the welding motorsport questions.

      Craig

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      • #4
        Hopes under everybody many publications the unique viewpoint

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        • #5
          Assuming you tested the coil the same way, bolt, 1/8" from block...

          You are basically left with:
          Bad cap/rotor - or weak spark.

          First thing, check your grounds back to the battery and check the battery itself. While the engine is cranking, the difference in voltage from the engine block to negative post on the battery should be less than 1 V. (this is sort of a load test). If its higher, clean all the connections and retest. BTW, I had once forgotten to put the ground strap back on the motor. The Motor grounded itself via the shifter cable - which promply fused/welded itself making it impossible to shift. So just because you have a ground, doesn't mean you have a good one.

          If there is a condenser (capacitor) might want to replace that just to be sure.

          A dwell meter will let you know if the coil is being fully energized.

          There are various tools that will tell you if a spark is strong enough. OTC makes an electronic version. There are spark gap simulators - essentially a controlled gap (bigger gaps require bigger voltages). The ultimate tool is an oscilloscope.

          BTW, high spark voltage is also a bad sign - means your gaps are too big. Normal ignition voltages are typically around 20K Volts (sometimes as low as 12K). As your spark plugs wear, the gaps get bigger and the voltages go up. A cracked spark plug can send voltages to 40KV

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