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  1. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    1228747 ECM and "AKWA" PROM chip. I replaced with the Cardone 77-8747 and put in Jet chip #289128. Is this the wrong Chip? The capability chart shows 89-90 Chev and GMC truck 5.7. Any possibility this van needs a different chip? Any thoughts? I attached the chart below. On a side note, I...
  2. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    THANKS good buddy
  3. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    More pics of codes and data.
  4. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    All powers and grounds are good at ECM back probing. Is it possible I installed the wrong PROM? It was a JET prom. Here are pics of scan data KOEO. Battery voltage shows 0.00. I also noticed that the prom ID number keeps randomly changing without touching anything.
  5. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    I will try that. Thanks.
  6. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    Are there any other grounds that I'm missing? I've replaced the head to frame ground. Replaced thermostat ground eyelet and cleaned mounting surface. I have the entire wiring harness exposed and don't see any issues with any wires. Wondering if I got a defective new ECM.
  7. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    Threw in temporary new battery, still no change. Repaired corroded positive cable end.
  8. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    Voltage at Battery is 12.3 volts. Battery load tested fine. I put a battery charger on the battery while looking at data and the scanner data went to 0.00 Battery Volts.... WTF. Swapped back old ECM and then the scanner showed 24 volts KOEO. Re-installed new ECM then it showed 14 volts (KOEO)...
  9. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    I meant the Engine Coolant Temperature sensor. Two wire plug next to the thermostat. Replaced along with pigtail harness.
  10. J

    1989 TBI 350 5.7 Grumman Kurbmaster electrical issue runs rough, PULLING MY HAIR OUT

    Working on a customers 1989 Grumman Kurbmaster with a 5.7 350 TBI. Came into the shop running rough and dying. Pulled up scanner data and found CTS showing -40 KOEO. CTS comes up to maybe 30-40 degrees when the truck is running and RPM'S are up. Goes slowly back to -40 and then dies at idle. TPS...

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