My vintage 1986 Corvette convertible recently developed a stumble that progressed to a no-run condition. It comes and goes sometimes starting but in a few minutes I get a SES (Service Engine Soon) light and it stalls. Read codes 33 (high MAF) and code 36 MAF (burnoff signal malfunction). After it stalls it won't restart.

So, I had a new MAF in the box as a spare and I tried it and still no start. It cranks but won't start. When I removed the MAF out came a fuel fog from the throttle body. I have the factory service manual and I have had a code 33 before but never a no-run condition ... only a stumble when I let off the gas. It was my MAF power relay that went bad last time and I replaced it with a new one only 3 months ago. It's not the MAF power relay because I tried a new one and it did not fix.

PS: Now that I replaced the Ignition Control Module (ICM), that solved the no-run condition. Why would it throw those codes for a bad ICM?

  • Welcome to Motor Vehicle Maintenance & Repair! If you have a "fuel fog from the throttle body", this to me would indicate you have fuel, so something else is amiss, like maybe you're not getting spark. Have you checked to ensure the engine is firing the spark plugs correctly? The MAF working or not should not affect the spark (IIRC). Commented Dec 12, 2018 at 19:04
  • Thanks @Paulster2 - I haven't checked for spark yet. I've only had about an hour to work on it in the dark. Good comment;)
    – 3dalliance
    Commented Dec 12, 2018 at 19:48
  • Is this a carbureted engine with a remote ign coil? (coil is not in the dist cap)
    – Moab
    Commented Dec 12, 2018 at 20:23
  • It is a Tuned Port Injection electronic fuel injection engine. The coil is in the HEI distributor cap. I'm thinking also that it might not be the relays at all but the ICM in the distributor.
    – 3dalliance
    Commented Dec 12, 2018 at 20:56
  • Checked for spark OK, checked fuel pressure 40-45PSI OK and put a new MAF power relay which did NOT fix it.
    – 3dalliance
    Commented Dec 13, 2018 at 13:19

1 Answer 1


Although not an answer to the code 33 & 36, The Ignition Control Module (ICM) was bad and fixed my no start condition. Tested for more than 45 minutes no problems, no service engine soon (SES) light and no codes.

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