Oct 24, 2017 - 05:26 AM
This video is about 1996 GMC Suburban with a 7.4L engine that had a deficient fuel supply system we identified during a state of health check at approximately 330k miles. The fuel pump was tested using the PicoScope measuring current, and with a fuel flow meter we were able to gauge the fuel system hydraulic circuit as well. The fuel pump and sending unit assembly were renewed due to rust and external piping deformaties. The pump was replaced although electrically it appeared to be ok, but since we had the fuel tank out of the vehicle we opted for renewal.
The main issue with this vehicle was that there was insufficient rest fuel pressure along with the system no longer recirculating fuel back to the tank. Newer vehicles now have fuel pressure regulators either built into the pump or use PWM controlled fuel pumps.
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