Fuel Pressure
- Begin basic diagnosis of fuel system by measuring system pressure. Turn ignition off. On 9-3, remove engine cover. Unscrew valve cap from fuel rail and connect fuel pressure gauge. On 9-5, disconnect banjo coupling at inlet to fuel injection manifold. Connect a fuel pressure gauge, using existing seals. On both models, hang pressure gauge vertically.
- Connect TECH-2 scan tool to Data Link Connector (DLC). Use scan tool to activate fuel pump. On 9-5, if scan tool is not available, connect fused jumper wire between fuses No. 8 and 19 to activate fuel pump. Leave fuel pump turned on until fuel pressure no longer rises. Pressure should be around 43 psi (3.0 kg/cm2 ). If fuel pressure is too high, go to next step. If fuel pressure is too low, go to step 4 . Let vehicle sit for 20 minutes and recheck residual pressure. It should be at least 33 psi. If pressure is less than specified, check for leaking non-return valve at fuel tank.
- Turn ignition off. Disconnect fuel return line from pressure regulator. Blow through line. If line is open, pressure regulator is defective and should be replaced. If line is blocked, remove blockage or replace with a new return line. Inspect one-way valve plugged into top of fuel pump assembly at tank. Replace if necessary. Retest system.
- Check fuel level. DO NOT rely on fuel gauge. Inspect for fuel system leaks. Test fuel pressure regulator. See FUEL PRESSURE REGULATOR . If fuel pressure regulator operation is not as specified, replace regulator.