Fuel System Pressure Test (4.0L)
- Perform FUEL PRESSURE RELEASE (4.0L PFI). Connect a 0-60 psi fuel pressure gauge to test port pressure fitting on fuel rail. Remove vacuum line from fuel pressure regulator. Start vehicle and note gauge reading. See FUEL SYSTEM PRESSURE SPECIFICATION table. Reconnect vacuum line and note gauge reading. See FUEL SYSTEM PRESSURE SPECIFICATION table.
- If fuel pressure is not 8-10 psi higher with vacuum line disconnected, inspect pressure regulator vacuum line for leaks, kinks or blockage. If fuel pressure is low, momentarily pinch shut hose section of fuel return line. If pressure remains low, inspect fuel supply line, fuel filter and fuel rail inlet for blockage.
- If fuel pressure rises, replace fuel pressure regulator. If fuel pressure is above specifications, inspect fuel return line for kinks and blockage.
FUEL SYSTEM PRESSURE SPECIFICATIONS
| Application | psi (kg/cm2 ) | |
|---|---|---|
| 2.5L TBI | 14-15 (1-10) | |
| 4.0L PFI | ||
| w/Vacuum Line Disconnected | 39 (2.7) | |
| w/Vacuum Line Connected | 31 (2.1) | |