Integra LS Coupe L4-1834cc 1.8L DOHC MFI (1997)
1. When the engine starts, fluid discharged from the discharge port starts to run through the metering orifice in the pump. The discharge volume
increases as the engine speed increases.
2. As the flow has already been regulated by the metering orifice when the engine speed is at or near the idle speed, a constant and regulated
amount of fluid is discharged until the engine speed reaches the middle speed range. As the engine speed increases, the pressure difference
between the ends of the metering orifice increases. A pressure difference is created between the top and bottom ends of the flow control valve,
too, pushing the flow control valve to open the by-pass passage. This allows the excess fluid to return to the inlet port preventing pressure at
the discharge port from rising excessively.
3. As the engine speed continues to increase, the flow control valve is pushed back further. When the engine speed reaches a given speed, the
return passage outside the metering orifice is connected to the inlet port, and the opening to the inlet port widens in proportion to the increase
in engine speed. This makes part of the fluid regulated by the metering orifice return to the inlet port of the pump; there by discharged fluid
from the pump is decreased slowly by this amount.
4. The orifice in the return passage regulates and maintains the flow of fluid discharged from the pump at a given level until the engine speed
reaches the high speed range.
PRESSURE RELIEF
Pressure outside of the metering orifice is directed to the bottom of the flow control valve. When the pressure builds up, the relief valve in the flow
control valve opens to relieve the pressure. As the flow control valve is pushed back by the pressure difference this time, the flow of fluid in the
bypass passage increases, controlling the pressure outside the metering orifice. The above operations are repeated to provide constant discharge
pressure from the pump.
