Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Chart A7 (1 Of 2) - Fuel System Diagnosis: Notes
When the ignition switch is on, the ECM will turn on the in-tank fuel pump. It will remain on as long as the engine is cranking or running and the ECM is receiving ignition reference pulses.
If there are no reference pulses, the ECM will shut off the fuel pump within 2 seconds after the key is turned on. The pump will deliver fuel to the TBI unit, where the system pressure is controlled to 9-13 psi (6.2-9.0 kg/cm2 ). Excess fuel is then returned to the fuel tank. The fuel pump test terminal is located in the left side of the engine compartment. When the engine is stopped, the pump can be turned on by applying battery voltage to the test terminal.
- Fuel pressure should be noted while fuel pump is running. Fuel pressure will drop immediately after fuel pump stops running due to a controlled bleed in the fuel system.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.