Wrangler L4-150 2.5L VIN P MFI (1993)
Fuel Pressure: Testing and Inspection
Fuel Pump Capacity Test
CAPACITY TEST PROCEDURE
1. Remove the cap from the pressure test port in the fuel rail.
Fuel Pressure Test
2. Connect a 0-414 kPa (0-60 psi) fuel pressure gauge to the pressure fitting on the fuel rail.
3. Start the vehicle. Pressure should be approximately 214 kPa (31 psi) with the vacuum hose connected to the pressure regulator. Pressure should be
269 kPa (39 psi) with the vacuum hose removed from the pressure regulator.
4. If the pressure is not to specification, check the following before replacing the fuel pressure regulator:
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Inspect the fuel supply and return lines/hoses for kinks or restricting bends
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Check the fuel pump flow rate. A good fuel pump will deliver at least 1 liter of fuel per minute with the hose section of fuel return line
pinched off. If the fuel pump does not pump adequately, inspect the fuel system for a plugged fuel filter or fuel pump inlet filter (sock).
Fuel pump flow rate can be checked with and old air conditioning gauge hose. Connect one end of the hose to the fuel test port on the fuel rail.
Place the other end of the hose into a container of at least 1 liter capacity. Run the fuel pump by installing a jumper wire across the power side of
the fuel pump relay connector. Re sure to pinch off the hose section of the fuel return line, or most of the fuel will be returned to the fuel tank.
NOTE: The fuel pressure regulator is not adjustable.
