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.
Fuel Pump Control
Fuel pump on and off and voltage variation control is accomplished through the ECU. Depending upon the system in use, control is accomplished by either varying voltage to the fuel pump or by turning fuel pump relay on or off. Some systems incorporate air regulator and fuel pump on and off controls simultaneously.
Fuel pump on and off control takes place as follows: ignition switch in "ON" position (operates for 5 seconds), engine running and/or cranking and engine stopped (stops in one second). Fuel pump voltage is approximately 9.4-13.4 volts except under the following conditions. Under these conditions, fuel pump voltage is approximately 13.4 volts: 5 seconds after ignition switch is turned off, during engine cranking, 30 seconds after engine starts, high engine temperature with idle switch off and low engine temperature.
Use the Manual With the Right Hardware
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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.
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