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.
System Inspection
- Check fuel leakage
- Check following item visually.
- Connector connection state.
- Damage/connection state for vacuum hoses connected to fuel line.
- Bent/pressed/twisted fuel line or fuel leakage.
- Has a problem found in this procedure?
YES
- Repair or replace it which has a problem, and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
NO
- Go to " 2 Check Low pressure fuel line" as follows.
- Check following item visually.
- Check low pressure fuel line NOTE:
- Be cautious that Fuel is explosive and an empty fuel tank can still contain explosive gases. When working on fuel system make sure to supply adequate ventilation to the work area. Do not smoke, and keep sparks and open flames away.
- The fuel system remains under pressure when the engine is not running. Release fuel system pressure before disconnecting any fuel line to reduce the chance of personal injury or fire damage to vehicle components.
- IG "OFF" and disconnect Fuel Pump Relay in Junction Box.
- Start-up and wait until it stops itself.
- IG "OFF" and connect Fuel Pump Relay.
- Install the fuel pressure gauge to the delivery pipe with the fuel pressure gauge adaptor.
- Activate the fuel pump, and with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.
- Measure the fuel pressure at idle.
Specification : 400 ~ 600 kPa (4.07 ~ 6.12 kg/cm2 , 58 ~ 87 psi)
- Is the measured fuel pressure within specifications?
YES
- Go to "COMPONENT INSPECTION " procedure.
NO
- Repair or replace according to the below table. And then, go to "VERIFICATION OF VEHICLE REPAIR " procedure.
Condition Possible Cause Fuel Pressure is too low Fuel filter, fuel pressure regulator, in-tank fuel hose or the fuel pump Fuel Pressure is too high Fuel pressure regulator, hose or pipe - Check high pressure pump
- Connect GDS to DLC (Data Link Cable).
- Start the engine and monitor "Rail Pressure Sensor" parameter on GDS at accelerating.
- Are the parameters displayed correctly?
Specification : the fuel rail pressure will be increased while accelerating the vehicle.
- Are the parameters displayed correctly?
YES
- Go to " 4 Check injector" as follows.
NO
- Repair or replace high pressure pump, and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
- Check fuel leakage in injector
- IG "OFF" after checking the fuel pressure test.
- Stop engine and check for a change in the fuel pressure gauge reading for 5 minutes.
Specification : After engine stops, fuel gauge reading is maintained for 5 minutes.
- Is the fuel gauge reading maintained?
YES
- Go to "COMPONENT INSPECTION " as follows.
NO
- There is a fuel leakage in injector. Replace it, and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.