Cherokee & Wrangler

NOTE: Cherokee and Wrangler models are equipped with a mechanical fuel pressure regulator located in fuel tank, inside fuel pump module. Excess fuel is returned to tank through fuel pressure regulator.

Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Remove test port cap. Install a 0-60 psi (0-4.2 kg/cm² ) fuel pressure gauge at test port.
Start engine and allow to idle. Fuel pressure should be 44.2-54.2 psi (3.1-3.7 kg/cm² ). If no fuel pressure exists, fuel pump relay control circuit may be defective. See DTC P1282: FUEL PUMP RELAY CONTROL CIRCUIT under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.
If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, go to FUEL PUMP VOLUME TEST .
If fuel pressure is more than specified, fuel pump is okay, but fuel pressure regulator is defective. Release fuel pressure and replace fuel pressure regulator. See FUEL FILTER/FUEL PRESSURE REGULATOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.
If fuel pressure is as specified, release fuel pressure. Remove test gauge hose. Install test port cap.