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  • 1990 HEI Injector Fuse Rating Question - Vin 8
  • 1990 HEI Injector Fuse Rating Question - Vin 8
  • 1990 HEI Injector Fuse Rating Question - Vin 8
  • 1990 HEI Injector Fuse Rating Question - Vin 8

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  1. #1
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    Default 1990 HEI Injector Fuse Rating Question - Vin 8

    In looking into suspected injector performance issues, I was testing
    a left and right bank load resistance at the fuse block and noticed there
    are two fuses, one for the left another for the right bank. My question
    relates to the amperage ratings for this car: Why are they not the
    same? I have reviewed the FSM and schematic diagrams for the
    vehicle and must be missing something obvious here. Would any of
    you wire guru's know the answer? I see where the DIS system on
    the other model Vin (J) might need additional amperage for a module,
    but am not finding why the HEI injector system would not use two fuses of
    the same rating. I looked pretty hard for an answer before asking
    this quesiton, so know I have thick skin and let me have it.

    Thank you

  2. #2
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    OO 85 2-Tone Blue, Z51, 4+3
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    Default

    Both of these circuits are hot in RUN and START. In other GM models these circuits are called ECM1 and ECM2. Or ECM A and ECM B. There are items on these circuits other than just the injectors. O2 sensor heaters, solenoid coils, stuff like that. Perhaps one circuit has a higher load than the other, hence the different fuse ratings?

    Fuses are to protect the wire from overload, not the devices connected to the circuit. The wiring gauge on the lower rated fuse circuit is possibly a smaller gauge.

  3. #3
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    Default Fuse Rating

    Dave,

    Thank you for taking the time to reply. I feel pretty good that I
    know what components are getting power in the vehicle and the
    circuits that are being protected. On this vehicle, I have yet to
    identify any additional solenoids, sensors or components beyond
    the fuel injectors being powered via the two fuses. I have seen
    on other GM vehicles that an additional source of power for the
    fuel pump is provided via these fuses, should a fuel pump relay fail.
    I am not seeing this logic on the Vin (8) 90 Vette my friend has.
    I do see that on the Vin (J) where the 20 amp fuse does power
    a module for the DIS, but nothing similar for the Vin (8) on the
    schematic diagrams. I will keep looking and thanks again for the
    reply.

    Paul

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