Fuel Pump Pressure Test
- Begin basic diagnosis of fuel system by determining fuel system pressure. Release fuel pressure. See FUEL PRESSURE RELEASE.
- On 2.5L engines, disconnect fuel supply hose. Connect Fuel Pressure Test Adapter (6539) between fuel supply hose and engine fuel line. Connect Fuel Pressure Gauge (C-4799) to Fuel Pressure Test Adapter (6539).
- Turn ignition on. Using Diagnostic Readout Box (DRB), access ASD Fuel System Test. ASD Fuel System Test will activate fuel pump and pressurize fuel system. If fuel pump pressure is at specification, fuel system is functioning properly. See FUEL PUMP REGULATED PRESSURE
table.
- If fuel pressure is more than specification, go to step 7). If fuel pressure is less than specification, record pressure. Repeat FUEL PRESSURE RELEASE procedure. Install fuel pressure gauge in fuel supply line at rear of vehicle between fuel tank and fuel filter.
- Turn ignition on and using DRB, activate fuel pump. Record pressure reading. If fuel pressure is 5 psi (34.5 kPa) more than first pressure reading, replace fuel filter.
- If no change in pressure reading is observed, gently squeeze fuel return hose. If fuel pressure increases, replace fuel pressure regulator. If no change in fuel pressure is observed, problem is plugged fuel pump inlet strainer or a defective fuel pump.
- If fuel pressure is more than specification, repeat fuel pressure release procedure. See FUEL PRESSURE RELEASE. Ensure fuel tank is at least half full. Install fuel gauge in fuel supply hose between fuel and fuel filter. Remove fuel return hose at fuel tank and connect an extension hose to return hose. Place hose in an approved container with at least a 2 gallon capacity.
- Turn ignition on. Using DRB, activate fuel pump. If fuel pressure is now within specification, check in-tank return fuel hose for kinking. Replace fuel pump assembly if in-tank reservoir check valve or aspirator jet is plugged.
- If fuel pressure is still more than specification, repeat FUEL PRESSURE RELEASE procedure. Disconnect fuel return hose from chassis fuel line (at engine). Connect fuel pressure gauge to fuel return hose and place other end of hose in an approved container with at least a 2 gallon capacity. Using DRB, repeat fuel pressure test. If fuel pressure is correct, check for restricted fuel return line. If there is no change, replace fuel pressure regulator.
FUEL PUMP REGULATED PRESSURE
| Application |
Pressure - psi (kPa) |
| Caravan & Voyager |
39 (269) |
| Dakota |
13.5-15.5 (93-107) |