Durango 4WD V8-5.9L VIN Z (1998)
Fuel Pressure: Testing and Inspection
Fuel Pressure Leak Down Test
Fig 11 Connecting Adapter Tool - Typical
Fig 12 Connecting Adapter Tool - Typical
NOTE: Use this test in conjunction with the Fuel Pump Pressure Test and Fuel Pump Capacity Test.
Check Valve Operation: The electric fuel pump outlet contains a one-way check valve to prevent fuel flow back into the tank and to maintain fuel
supply line pressure (engine warm) when pump is not operational. It is also used to keep the fuel supply line full of gasoline when pump is not
operational. After the vehicle has cooled down, fuel pressure may drop to 0 psi (cold fluid contracts), but liquid gasoline will remain in fuel supply
line between the check valve and fuel injectors. Fuel pressure that has dropped to 0 psi on a cooled down vehicle (engine off) is a normal condition.
when the electric fuel pump is activated, fuel pressure should immediately rise to specification.
Abnormally long periods of cranking to restart a hot engine that has been shut down for a short period of time may be caused by:
^ Fuel pressure bleeding past a fuel injector(s).
^ Fuel pressure bleeding past the check valve in the fuel pump module.
Procedure
1. Disconnect the fuel inlet line at fuel rail.
-
On some engines, air cleaner housing removal may be necessary before fuel line disconnection.
2. Connect the appropriate Fuel Line Pressure Test Adapter Tool (number 6539, 6631, 6541 or 6923) between the disconnected fuel line and fuel rail
(Fig. 11) or (Fig. 12).
3. Connect the 0-414 kPa (0-60 psi) fuel pressure test gauge (from Gauge Set 5069) to the test port on the appropriate Adaptor Tool.
-
The fittings on both tools must be in good condition and free from any small leaks before performing the proceeding test.
4. Start engine and bring to normal operating temperature.
5. Observe test gauge. Normal operating pressure should be 339 kPa +/- 34 kPa (49.2 psi +/- 5 psi).
