Fuel Tank, Lines and Pump
with Instructional Video
Fuel delivery in a TBI system
is CRITICAL to achieving optimum performance. Any
deviation from these instructions or the parts supplied can result a
number of problems at first start up.
Before adjusting fuel pressure be certain the gas tank is at
least half full. If the fuel pressure is not steady chances are that
air is being picked up from the fuel tank because the level is too low.
The fuel pump and regulator supplied with my kits may change over
time but the installation principle remains the same.
Installation of the
regulator (preferred location and new style regulator),fuel lines and the fuel pump.
Your fuel pump may differ from the one shown but the
installation principle is the same.
Pump & Fuel Line Routing
A dirty fuel
tank and/or dirty fuel lines can have a major impact on how your car
performs with TBI. For that reason I strongly recommend that you remove
your tank and have it professionally purged, cleaned and tested. This
would also be the perfect time to have a bung for the return line fitting
and for the tank outlet. Both bungs should be 1/4" NPT.
Tank Outlet Bung 1/4" NPT
Return Line Bung 1/4" NPT
Now that you
have a clean tank, you're ready install the correct sized fittings and
plan the best way to run your fuel lines. With the tank in place,
install a shut off valve and the return line fitting. The shutoff valve
will make working around the fuel lines much easier in the future,
including a yearly fuel filter change.
Shut Off valve screws
directly into the tank outlet.
The fuel filter hangs
directly below the shut off.
DO NOT USE your existing steel fuel lines as the
supply line from the tank to the regulator. They are
TOO SMALL and won't deliver
enough fuel to the regulator and the injectors. You MUST USE the 5/16"
or 3/8" ID
hose as the supply line. When
using AN connectors or braided hose
it must be 5/16" or 3/8" inside diameter or larger.
ultimately decide to run the fuel supply hose from the fuel pump to the
regulator is up to you but keep in mind the following:
radius bends to avoid any kinks.
from touching or running close to any major heat source such as the
away from any moving parts such as the driveshaft or u-joints.
This is as sharp a hose
radius as you should make.
The return line
is run from the regulator back to the fitting that was installed in the
tank. This allows any excess fuel not used by the injectors to be
returned to the tank. The return MUST go to the tank and NOT to the
This right angle fitting was put in
the top of the tank
on the driver's side. It could also have gone on the
side of the tank.
The easiest way
to run the return line is to re-use the old steel supply line that
already runs from the fuel tank to the old mechanical pump. IMPORTANT:
if you plan on re-using the old steel line, you must remove & replace
the few sections of existing rubber hose that connects sections of steel
line. The old rubber pieces gave probably deteriorated with age and must
be replaced. Before replacing them, blow compressed air through the
steel lines to make sure they are clean and clear of any debris. The
return line is a low pressure line so 5/16" fuel hose can be used for
the connection from the end of the steel line at the mechanical pump to
Plumbing the fuel system consists of four
parts; suction, high pressure, return, and regulated pressure.
Suction: The section of line
that supplies fuel from the tank to the electric fuel pump.
High Pressure: This
section of line is from the electric fuel pump to the fuel pressure
regulator. Line pressure in this section is 30 to 40 psi and the fuel
filter is located here.
Return: This smaller line returns
excess fuel from the regulator back to the fuel tank. This section is
usually very low pressure at less than 2 psi.
Regulated: This is the
regulated pressure out of the fuel pressure regulator that supplies the
TBI injectors. Pressure in this section is typically 14 psi.
Shown below is the system used on Aaron Cropley's 1971 TR6. Another
example from a 1975 TR6 can be
The original fuel line from the TR6
tank is 5/16" steel line coming out the bottom of the tank.
Because the source is at the bottom, gravity will drain the
entire tank if there is a leak. The electric pump used for
TBI requires a 5/16" or 3/8" supply line, however because
gravity supplies the pump, the 5/6" line is sufficient for
the TR6. On this car we added a fuel shut off (must be a
full flow type). A short section of hose connects the shut
off to the plastic filter.
Even though the fuel
pump has a filter screen, it's best to install a filter
between the tank and the fuel pump. There's no telling
what's collected in the bottom of a 30 year old gas tank!
This is the section that carries the
high pressure output from the fuel pump. Steel 3/8" brake
line connects to the pump's output and heads forward along
the left hand frame member. A 3/8" coupling joins another
section of steel tubing and connects to the fuel filter. The
filter used is a common GM fuel injection filter, NAPA 3481.
The steel tubing requires adapters to mate with the filter,
2 of a NAPA WH 1446 fitting. The 5/16" line crossing over
the top of the pump is the return line back to the fuel
You can also use properly
sized fuel hose or Teflon line in place of the steel lines.
A filter after the fuel pump can
also be added for extra security. In this case a GM filter
has been installed.
The regulator marks the end of the
high pressure section. The regulator supplied comes with an
assortment of fittings to ease installation. Please
review the FAQ
section for a complete description and installation
process for the regulator.
The return line returns excess fuel
from the regulator back to the gas tank in the trunk. There
is little or no pressure in this section so regular fuel
hose is perfectly suitable. Starting at the regulator 5/16"
fuel hose connects to steel 5/16" tubing. The steel line
drops down from the regulator, runs across the backside of
the front frame cross-member and is connected to the original
TR6 steel fuel line. The connection between the two steel
sections is made with a short piece of 5/16" rubber hose at
the same location as there was a short hose splice in the
The yellow arrow shows the new
return line from the regulator connecting to the old steel
fuel line which was reused for returning gas to the tank. Fuel returns in the original TR6
supply line and back near the new pump, is coupled to 5/16"
plastic line with a short section of rubber hose. I prefer
to use fuel injection style hose clamps whenever possible.
The plastic tubing squeezes up through a rubber grommet in
the trunk floor alongside the tank vent hose. It continues
up to the the top of the gas tank and connects to the vent
nipple at the left end. The hose that originally attached to
that vent nipple is plugged off. If you don't have a
connection at your tank for the return line, you'll have to
have one soldered in.
If your tank doesn't
have these vent nipples, you will need to make provisions
for the return. Either have a repair shop add a 5/16" nipple
or contact me for a sender unit with the return built in.
The tank connection is something you will need to take care
of on your own. Provisions can be made long before starting
Here we are at the end of the line
where all the previous plumbing delivers fuel at 12 PSI. Two
regular 5/16" hoses (minimum size), connect from the
regulator to each of the fittings on the carb bases. Best
to have the regulator within 18" of the injectors.
The regulator show here is an older
style than the Aeromotive that we currently provide but the
connection concept is the same.
There are many other
ways to run this plumbing, especially the high pressure
section. Some suppliers recommend a high pressure "push
lock" hose. High pressure plastic tubing could be run the
entire way or even high pressure rubber hose. Personally I
like to use steel lines under the car but newer cars are
using plastic or Teflon lines.
Safety is a concern with the fuel pressure regulator so an
off the shelf alternative is best. The regulator must be the
recirculating type to work properly. Most of the aftermarket regulators have a small line
used to sense intake manifold vacuum. In case of a ruptured
diaphragm, fuel would escape down that line and flood the
engine. Those same regulators when used with TBI should NOT
be plumbed to sense manifold vacuum. That line could be
piped to the carb's temperatures compensator port, run back to
the fuel tank, or vented in a non smog application.
Fuel filters are also open to change. For Aaron's car the GM
filter was chosen as it is available anywhere and suitable
for connection with steel line. Ford uses a filter that is
designed for quick disconnects but works well with hose.
Patton Machine LLC - Custom
Components for Classic Cars