Other Fuel System Related Problems of the 2020 Chevrolet Express

Other Fuel System problem

The vehicle is experiencing an under-chassis manufacturing wiring harness restriction (connector x185) that was installed too tightly from the factory, dropping the 5-volt reference power circuit down to 0 volts under load. This intermittent electrical failure completely starves the fuel pump, causing the fuel loop pressure to drop to a dangerous 43. 5 psi while driving (gm factory specification is 55–100 psi). This electrical breakdown simultaneously chokes the fuel tank vapor loops, causing the fuel tank pressure to spike to an extreme -1100 vacuum pressure parameter. This results in severe engine hesitation, random vehicle starving of fuel, an abysmal 9. 9 mpg average compared to the 13 mpg combined standard, and an automated network communication failure resulting in four distinct audible dashboard warning beeps. It also cuts power to the brake pedal position sensor, crashing the stabilitrak traction control system. This creates a severe, immediate safety hazard under heavy highway driving conditions. This active powertrain hazard has been verified by a certified independent service center via secondary diagnostic data stack logs. Macmulkin Chevrolet is currently holding the commercial vehicle and explicitly refusing to execute the necessary wiring harness circuit trace to resolve the underlying hazard because a dashboard light is not illuminated, leaving a documented safety defect completely un-repaired on a commercial asset.