Thread: Plumbing fuel line

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Roger and Steve, as much as I respect your opinions on not mounting a filter before the pump, here is info straight off of Holley's installation instruction sheet:
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NOTE: To ensure pump life and flow efficiency, a quality fuel filter, such as Holley P/N 162-515 must be installed between the tank and each pump inlet. The filter should be supported in such a manner that it does not hang from the fuel lines.
4. Connect the fuel line from the tank to the fuel filter and then to the inlet port of the pump. Connect the carburetor delivery line to the outlet port of the pump and to the regulator (for the 12-150) located near the carburetor inlet. See Figure 1. The fuel pump inlet and outlet ports take a 3/8” NPT fitting, therefore a 3/8” or larger fuel line is recommended.
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I've pretty much always used Holley electric pumps in cars, even some daily drivers that saw lots of miles, and I have ALWAYS used a filter before the pump. Holley pumps will stick open internally with even a spec of dirt ( I had some fiberglass dust in my 27 tank that kept getting even through the filter, the specs were that small, but they would jam the check valve open and kill the pressure)

This is also the way we always rigged a boat engine, be it outboard or inboard, with the filter before the pump. Think of every outboard engine you have seen, the water separating filter is mounted between the tank and the motor, and the pump is on the motor. Those pumps are wimpy compared to a Holley and they draw just fine through the filters.

And here is what Carter says on their instruction sheets:

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The universal fuel pump should be mounted below the
fuel tank, as all pumps do not have equal lift capabilities.
Also, the pump must be mounted below the carburetor
to avoid possible vapor lock conditions occurring.
Under no circumstances should the pump be mounted
in the trunk, inside the vehicle, or in the engine
compartment; personal injury could occur in the
event of a fuel line rupture.
NOTE: Not al universal electric fuel pumps are
capable of a pul-through arangement with
an existing mechanical fuel pump system. Check
information on al universal electric pumps.
PRESSURE SAFETY SWITCH A-68301
INSTALLATION INSTRUCTIONS
A pressure switch should always be used in conjunction
with the Universal In-Line Electric Fuel Pump. ICC Motor
Carrier Safely Regulations stipulate that the fuel pump
must not continue to operate after the engine stops. The
Safety Interlock Circuit stops the electric fuel pump when
the engine stops even though the ignition switch is not
turned “Off.” The pressure switch is a single-pole, doublethrow,
diaphragm-actuated switch. Terminals P (Pump)
and S (Start) are normally closed; terminals P (Pump) and
I (Ignition) are normally open. This allows the fuel pump
to operate and fill the carburetor while the engine is
cranking. When oil pressure exists (2 to 4-1/2 psi), the
P and S terminals are opened, and the P and I are
closed. The diaphragm is treated to withstand pressure
up to 150 psi.
If the oil pressure drops below 2 psi, the connection
between P and I opens and the fuel pump stops. This
also protects the engine from severe damage if an oil
line is broken or the oil level in the crankcase becomes
extremely low.
Full battery voltage must be available to the pump when
the ignition switch is in the start or run position. Do not
connect to the ignition coil, as a ballast resistor may be
built into the wire.
Safety Interlock System
The pressure switch should be installed
at a convenient location in the engine oil
pressure system. In some instances, it may
be necessary to install a “T” fitting below
the existing oil gauge sender or
dashlight unit.
Wires should be 18-gauge insulated,
or heavier, routed so as to protect
them from exhaust heat, and
anchored securely at frequent
intervals to prevent chafing.

(Here is the line that is of interest to us in this discussion)

Always mount a good quality fuel filter on the inlet side
of the pump. Failure to do so will void the warranty.
Do not mount the pump near exhaust system
components, as heat contributes to vapor lock.
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This is just the way I have been taught to do the pump/filter installation, both in my car hobby and my marine profession.

Don