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I've got a 1998 malibu response with effectively a marine-cammed SBC350 in it. Ran great and died when hot twice, and now I have no spark, at all.

I threw a new coil at it, to no avail. My current test setup is:

  • single coil wire straight to a spark plug, sitting on a bolt on the motor as a path to ground (this bypasses the cap and rotor)
  • Distributor pulled but plugged in, rotating it by hand
  • key on, all safety switches in their working position

I've tested and I see 12 volts to the coil. I've also tested the distributor with a test light, and it grounds the C pin as it rotates, as it should. The ECU is alive, because it's firing the fuel pump and the injectors as I rotate the distributor. But yet I have absolutely no spark.

Edit: If I ground the coil manually with a wire, I get a very strong spark. The wire between the C pin of the distributor and that pin on the coil tests out with continuity using a multimeter.

What further steps can I take to diagnose this issue? Every component seems to be in working order, but when they come together, something breaks.

Also to note - it's a 98 GM HEI ignition module. Every mechanic I've spoken with thus far curses that particular module as being an unreliable, untrustworthy piece of junk. I'm tempted to blame it even though it tested fine, but that costs me 350$

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  • Do you have a good ground from engine to body and/or battery?
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Apr 29 at 18:18
  • I believe so - the injectors, starter, and fuel pump run fine, and as I said I have good spark when I manually ground the coil
    – Brydon Gibson
    Commented Apr 29 at 18:24
  • How are you manually grounding the coil? Why aren't you replicating that "normally"?
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Apr 29 at 20:01
  • What do you mean "normally"? I have a wire in the C terminal of the coil, and I'm tapping it against the block
    – Brydon Gibson
    Commented Apr 29 at 23:45
  • Why aren't you just going with what works? If you are getting spark with running a wire in the C terminal of the coil and tapping that against the block to get spark, why aren't you just doing that to get a spark?
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Apr 30 at 0:19

1 Answer 1

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The issue here was a break in the wiring right at the connector to the coil. I have spark now, however the motor still doesn't run, and I'm not sure why.

Contrary to what I expected (the ECU intercepts C from the distributor), there should be continuity between the distributor and the coil

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2
  • Is compression good? Is spark timing correct? Are spark plugs wet or smell of fuel? While you're working on old school distributor ignition and carburetor, old school basic diagnostics still applies to determine a fuel or spark issue prevents engine running.
    – F Dryer
    Commented May 2 at 17:08
  • It was a very weak spark - I had pulled the ignition module out of the electronic 'distributor' and when I put it back in, corrosion caused high resistance between the ignition module and the distributor case.
    – Brydon Gibson
    Commented May 6 at 14:33

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