Fuel System Pressure Test

CAUTION: Check fuel system pressure only when fuel cylinders are half full or more.

1. Remove engine cover. Refer to Engine Cover removal/installation.
2. Remove air filter housing.
3. Remove service port cap from service port on fuel rail.

Fig.8 Fuel Pressure Gauge Attachment:

4. Attach 0 - 300 psi pressure gauge to service port (Fig. 8). The DRBIII Scan Tool along with the PEP module, the 500 psi pressure transducer, and the transducer-to-test port adapter may also be used in place of the fuel pressure gauge.
5. Start engine and bring to operating temperature. Minimum fuel injector operating pressure is 110 psi. Maximum operating pressure is 125 psi.
Proper fuel system operating pressures will depend on:
- Regulated fuel cylinder pressure (at low-pressure side of fuel pressure regulator)
- Engine temperature
- Outside ambient temperature
- Condition of low-pressure fuel shut-off solenoid
- Condition of fuel injectors
- Condition of high-pressure fuel shut-off solenoid and solenoid relay
- Engine load requirements

6. If operating pressure is above 125 psi, with fuel cylinders half full or more, and engine fully warmed up, replace fuel pressure regulator. Refer to Fuel Pressure Regulator Removal/installation.
7. If pressure is lower than 110 psi:
a. Be sure cylinders have fuel.
b. Be sure all 4 fuel control valves are fully opened.
c. Be sure manual gas shut-off valve is opened (parallel with fuel line).
d. Be sure there are no kinks or bends in any of fuel tubes.
e. Use the DRB Scan Tool to perform a test of the Low-Pressure Fuel Shut-Off Solenoid.
f. Use the DRB Scan Tool to perform a test of the High-Pressure Fuel Shut-Off Solenoid.
g. Use the DRB Scan Tool to perform a test of the fuel injectors. After tests and repairs have been completed:

8. Remove pressure test gauge.
9. Install service port cap to fuel rail.
10. Check system for leaks. Refer to Testing For Gas Leaks for procedures.
11. Install air filter housing.
12. Install engine cover.