Prelude L4-2056cc DOHC (1990)
Fuel Pressure: Testing and Inspection
1. Relieve fuel pressure.
a. Disconnect the negative battery cable.
b. Remove the fuel tank filler cap.
c. Use a box end wrench on the 6mm service bolt at the top of the fuel filter, while holding the special banjo bolt with another wrench.
Fuel Filter Service Bolt
c. Place a rag or shop towel over the 6mm service bolt and SLOWLY loosen the 6mm service bolt one complete turn.
Throttle Body Assembly Exploded View
2. Remove the service bolt on the top of the fuel filter while holding the banjo bolt with another wrench and attach the fuel pressure gauge.
3. Start the engine. Measure the fuel pressure with engine idling and the vacuum hose of the fuel pressure regulator disconnected.
PRESSURE AT IDLE SHOULD BE: 35-41 psi (2.45-2.85 kg/cm2)
4. Reconnect the vacuum hose to the fuel pressure regulator.
PRESSURE AT IDLE SHOULD BE: 29-35 psi (2.04-2.45 kg/cm2)
5. If the fuel pressure is not as specified check the fuel pump. If the fuel pump is okay, then check as follows:
1. If the pressure is higher than specified:
a. Pinched or clogged fuel return hose or line.
b. Faulty fuel pressure regulator.
2. If the pressure is lower than specified:
a. Clogged fuel filter.
b. Faulty fuel pressure regulator.
c. Leaking fuel line.
