Fuel Pressure Regulator: Description and Operation

Digifant II Fuel Pressure Regulator:

Digifant Fuel Delivery Components:

The Fuel Pressure Regulator maintains a constant fuel pressure in the fuel rail and to the fuel injectors. It is attached to the down stream end of the fuel rail.

When fuel pressure exceeds 44 psi (3.0 bar) above intake manifold pressure, the Fuel Pressure Regulator diaphragm is forced upward opening the fuel return port. This allows excess fuel to flow into the fuel return line and back to the fuel tank. The Fuel Pressure Regulator also has a vacuum hose attached that monitors intake manifold vacuum. Manifold vacuum works against the Fuel Pressure Regulator diaphragm spring, so as manifold vacuum increases it helps compress the diaphragm spring lowering the regulated fuel pressure in the fuel rail. Like wise as manifold vacuum decreases fuel pressure increases to the pre-set maximum of 44 psi (3.0 bar) at 0 in. vacuum. This causes a slightly richer fuel mixture for low manifold vacuum, (high engine load) conditions. Under high manifold vacuum, (low engine load) conditions such as idle, the fuel pressure will be slightly lower than 44 psi (3.0 bar).