Fuel Pressure Test

NOTE: The fuel system employs a vacuum assisted pressure regulator. System fuel pressure should be approximately 214 kPa (31 psi) with the vacuum line connected to the regulator. With the vacuum line disconnected from the regulator, fuel pressure should be approximately 269 kPa (39 psi). This is 55-69 kPa (8-10 psi) higher.

Fuel Pressure Test:

PROCEDURE
1. Connect the 0-414 kPa (0-61 psi) fuel pressure gauge (from Gauge Set 5069) to test port pressure fitting on fuel rail.

2. Remove vacuum line from pressure regulator.

3. Start the vehicle.

4. Note gauge reading. With vacuum line disconnected, fuel pressure should be approximately 269 kPa (39 psi).

5. Connect vacuum line to pressure regulator. Note gauge reading. Fuel pressure should be approximately 214 kPa (31 psi).

6. Fuel pressure should be approximately 55-69 kPa (8-10 psi) higher with vacuum line removed from regulator. If not, inspect pressure regulator vacuum line for leaks, kinks or blockage.

Fuel Return Line:

7. If fuel pressure is low, momentarily pinch shut the hose section of the fuel return line.

CAUTION: Fuel pressure will rise to as much as 95 psi when the fuel return line is pinched shut. Shut engine down immediately after pinching off fuel return line.

If fuel pressure remains low, inspect the fuel supply line, fuel filter, and fuel rail inlet for blockage. If fuel pressure rises, replace fuel pressure regulator.

8. If fuel pressure is above specifications, inspect the fuel return line for kinks and blockage.

9. Check the fuel pump flow rate (capacity). Refer to Fuel Pump Capacity Test. 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 the filter sock (at the fuel pump inlet).

10. 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 feed side of the fuel pump relay connector. Be 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.