Checking Fuel Pressure
- Disconnect fuel hose on fuel filter outlet side and install fuel pressure gauge. Replace pump fuse. Start engine and check fuel line connections for leakage. Check fuel pressure with engine idling. Record fuel pressure gauge reading.
- Disconnect and plug vacuum hose from pressure regulator and immediately note fuel pressure. Record fuel pressure gauge reading. See REGULATED FUEL PRESSURE table.
- Connect a hand-held vacuum pump to fuel pressure regulator. Start engine and watch indication of fuel pressure gauge as vacuum is changed. Fuel pressure should decrease as vacuum increases. If result is not as specified, replace fuel pressure regulator.
REGULATED FUEL PRESSURE
| Application | At Idle Without Vacuum psi (kg/cm2 ) | At Idle With Vacuum psi (kg/cm2 ) |
|---|---|---|
| G20 | 43 (3.0) | 36 (2.5) |
| M30 & Q45 | 43.4 (3.05) | 34 (2.4) |