Start engine. Warm to normal operating temperature. Turn ignition off. Release fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE . Remove plug bolt on fuel rail. Install coupling, pressure gauge and hose to fuel rail. See Fig 1 . Verify battery voltage is 11 volts or greater. Start engine and ensure no leakage exists at pressure gauge connection. Turn engine off.
Turn ignition on to operate the fuel pump for 3 seconds. Turn ignition off. Repeat test 3-4 times and re-verify the fuel pressure. Refer to the appropriate FUEL PUMP PERFORMANCE table and/or the REGULATED FUEL PRESSURE tables. Start engine. Measure fuel pressure at idle. Turn ignition off.
If pressures are not within specification, check for defective fuel pump, pressure regulator or restriction in fuel system. See CIRCUIT TESTS . Repair as necessary. Remove fuel pressure gauge and start engine to ensure no fuel leakage exists.

Fig 1: Testing Fuel System Pressure

Courtesy of SUZUKI OF AMERICA CORP.

FUEL PUMP PERFORMANCE

Application

⁽¹⁾ psi (kg/cm² )

X-90

⁽²⁾ 36.0-43.0 (2.5-3.0)

⁽¹⁾	Key on and engine off.

⁽²⁾	Pressure should maintain at least 26 psi (1.8 kg/cm² ) for one minute after fuel pump is turned off.

REGULATED FUEL PRESSURE

Application

⁽¹⁾ psi (kg/cm² )

X-90

⁽²⁾ 30.0-37.0 (2.1-2.6)

⁽¹⁾	With engine idling.

⁽²⁾	Pressure should maintain at least 26 psi (1.8 kg/cm² ) for one minute after fuel pump is turned off.

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.

Safety Warning

Fuel Pressure Test (X-90)