Mallory Ignition ACCEL CHEVROLET APPLICATIONS (including LT-1) 74022 - Manual (Page 7)

ACCEL/DFI ACCEL/DFI
ACCEL/DFI has two high pressure fuel pumps currently
available, an external mount fuel pump, part number 74701,
which can support up to 500 horsepower @ 45 PSI. The
second pump ACCEL/DFI offers (part number 74702) can
support up to 840 horsepower @ 45 PSI, this fuel pump can be
mounted in the fuel tank or on the frame rail. You can use
part number 74710 to mount this pump onto your frame rail.
Regardless of the fuel pump used, be sure to mount your fuel
pump near the tank at a point below the tank level, in a
protected area. System components must also be protected
and shielded from exhaust heat and engine compartment
heat as well as road damage.
Fuel Pump Wiring
The fuel pump requires a 12 volt source. If your vehicle was
an EFI vehicle originally, and already has a fuel pump
installed, you still MUST connect the +12 VDC side of the
fuel pump to the ACCEL/DFI main harness (red wire with
white tracer). The +12 VDC will come from fuel pump relay
via the red wire with white tracer in the main harness. The
fuel pump relay is already an integral part of the main
harness and is controlled by the ECM, therefore no wiring is
necessary for the relay. A pump will draw between 4 and 8
amps of current depending on size and fuel system pressure,
so 14 gauge wire should be used from the pump to the red
wire with white tracer. Also be sure to solder the connection
between these two wires. The ground for the fuel pump can
be at any clean, paint-free point on the chassis to the negative
(-) terminal of the fuel pump. Make sure that wiring between
the fuel pump and the engine compartment does not hang
below the vehicle, interfering with rotating parts or become
exposed to excess heat.
Mechanical Pump Removal
If your engine was carbureted, be sure to either cap off the fit-
tings on your mechanical pump or remove the pump and
cover the opening with a block off plate.
High Pressure Fuel Filter Mounting
Locate the high pressure fuel filter at the outlet of the high
pressure fuel pump on the frame rail. It is recommended to
place a filter between the fuel tank outlet and the pump inlet
if the pickup tube in the tank does not have a filter. Failure to
do so can result in fuel pump damage. ACCEL/DFI high
pressure fuel filters, part number 74720, requires 3/8”
Saginaw fittings. If your fuel line does not have these fittings
you can use part number 74721, these adapter fittings will fit
the 74720 filter and allow you to use a 6AN fitting.
Routing High Pressure Fuel Hose
At this point the high pressure circuit of the fuel system can
be plumbed (refer to figure G, Page 28). If the existing fuel
supply line cannot sustain 150 PSI pressure (DFI recom-
mends a fuel line rated to at least 330 PSI), then it must be
replaced with high pressure fuel line/tubing. Remember,
with a carburetor, your fuel system operated at about 6 PSI.
However, with fuel injection, the system operates around 50
PSI of fuel pressure. Never take any chances. If in doubt,
replace the hose. You will need a minimum of 3/8” ID sup-
ply line and 5/16” ID return.
Dual Fuel Tanks
It is important to note that for vehicles with either two fuel
tanks and/or class “A” RV’s it is highly recommended that a
boost pump be installed in each tank and feed through a
multi port switching valve, especially when operating in hot
11 10
VII – FUEL PUMP MOUNTING AND
HIGH PRESSURE LINE INSTALLATION