Edelbrock 3550 - Manual (Page 6)

6
Pro-Flo EFI Installation Instructions
©2005 Edelbrock Corporation
Brochure No. 63-0115 Rev. 10/05
FUEL SYSTEM
Because your Edelbrock Pro-Flo system controls fuel delivery very differently than a carburetor, some conversions to your fuel system are
necessary. Pro-Flo electronic fuel injection requires high and constant fuel volume and fuel pressure. For this reason, a good primary fuel line is
critical. The Pro-Flo system includes a 3/8-inch high pressure fuel line which must be used as the primary fuel line. The fuel that bypasses the
injectors must be returned to the fuel tank via a return fuel line. If your vehicle is already equipped with a fuel pump bypass line, this line can be
used as the return fuel line. If not, the original primary line may be used as the return line. If desired, an 8 foot length of 5/16 ID rubber hose is
supplied for use as the return line.
Many late-model cars are equipped with an additional fuel line which runs to a charcoal canister mounted on the driver side of the vehicle. This
line MUST be re-installed after the fuel system conversion and MUST NOT be used as the return fuel line.
FUEL PUMP AND FILTER
The Pro-Flo system uses a single Edelbrock high-pressure electric fuel pump which is
capable of pumping 50 psi. The pump relay will shut down the pump if it does not receive an
engine-run signal from the ECU, as in the case of a stall. This safety precaution is necessary
when using a high-pressure fuel line. The provided fuel filter should be mounted between the
engine compartment and the fuel pump to allow fuel to be pushed through the filter rather
than drawn through. Electrical connectors should face the front of vehicle. Make sure the
fuel pump is mounted at or below the bottom of your fuel tank. If the pump is mounted above
this point, fuel pump failure will occur.
FUEL PRESSURE REGULATOR
Fuel pressure is as important as fuel volume, particularly in fuel injection. The Pro-Flo fuel
pressure regulator maintains a constant pressure at the injectors with a spring loaded by-
pass to the return fuel line. Manifold Absolute Pressure references the regulator diaphragm
to maintain constant pressure across all 8 injectors, regardless of fluctuating manifold
pressure (vacuum) level. The fuel that is not injected is returned to the fuel tank via the return
fuel line.
RETURN FUEL LINE
Due to the high fuel pressure used by the Pro-Flo system, the supplied 3/8-inch high pressure fuel line MUST be used as the primary
fuel line, and a bypass fuel return line must be installed. There are three options for installing a bypass return line.
1. Use the 5/16 rubber fuel line provided with the system as the fuel return line.
2. Use the vehicle’s existing primary line as the fuel return line with modification to the pick up as described below.
3. Use the vehicle’s existing return line (if so equipped) as the fuel return line. This option applies only to vehicles previously equipped with fuel
injection. If the vehicle is not already equipped with a return line, some fuel tank modifications are required for routing the return line
through the sending unit plate back into the tank. The first two methods listed below require some welding and should be done by a
professional radiator or fuel system repair shop.
Tank Side
Engine Side