1991 Geo Tracker LSi, AutomaticFACTORY OEM SERVICE PROCEDURE

Chart A-7, Fuel System Pressure Test: Notes

Fuel pump delivers fuel to fuel rail and fuel injectors, where fuel pressure is maintained by pressure regulator.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Release fuel pressure before disconnecting fuel lines. Operate fuel pump by installing fused jumper wire between Black/White and Pink/Black wire terminals on fuel pump relay and turning ignition on. Fuel pump relay is mounted on ECM, located under left side of instrument panel, near kick panel.
  2. Restricted fuel flow can cause fuel pressure to decrease, resulting in driveability problem.
  3. Restricting fuel return hose allows fuel pump to obtain maximum fuel pressure. With ignition on, fuel pressure should be greater than 56.9 psi (4.0 kg/cm2 ).
  4. This determines if high fuel pressure is caused by fuel hose restriction or defective pressure regulator.
  5. This checks for a leaking pressure regulator.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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