RAM 1500 Van V6-239 3.9L Magnum (1995)
Fuel Pressure: Testing and Inspection
Fuel Pressure Leak Down Test
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:
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Fuel pressure bleeding past a fuel injector(s).
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Fuel pressure bleeding past the check valve in the fuel filter/fuel pressure regulator.
1. Engine OFF. Disconnect the fuel inlet line at fuel rail. The fuel line-to-fuel rail connection is made at the rear of the engine. Remove air cleaner
housing before tool connection.
Connecting Adapter Tool
2. Connect Fuel Line Pressure Test Adapter Tool number 6539 (5/16 in.), or Adapter Thol number 6631 (3/8 in.) between the disconnected fuel line
and fuel rail. Adapter Tool connection is made at rear of engine.
3. Connect the 0-414 kPa (0-60 psi) fuel pressure test gauge (from Gauge Set 5069) to the test port on either tool 6631 or 6539. 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 241-310 kPa (35-45 psi).
6. Shut engine off.
7. Pressure should not fall below 24 psi for five minutes.
8. If pressure falls below 24 psi, it must determined if a fuel injector, the fuel module mounted fuel pressure regulator or a fuel tube/line is leaking.
9. Again, start engine and bring to normal operating temperature.
10. Shut engine off.
11. Checking for fuel injector leakage: Clamp off the rubber hose portion of either tool 6539 or 6631 between the disconnected fuel tube (line) and
test port inlet. If pressure now holds at or above 24 psi, a fuel injector or the fuel rail is leaking.
12. Checking for fuel pressure regulator or fuel tube leakage: Clamp off the rubber hose portion of either tool 6539 or 6631 between the fuel rail and
test port inlet. If pressure now holds at or above 24 psi, a leak can be found at a fuel tube/line. If no leaks are found at fuel tubes or lines, replace
the fuel filter/fuel pressure regulator.
