Below I have posted the steps from the Ford Workshop Manual for
draining the tank. To sum up the procedure, you first relieve the
system pressure. Then you disconnect a fuel line under the vehicle and
connect a hose that runs to a catch container. Finally the fuel pump is
hotwired to pump the tank dry.Method of Draining
1. Loosen fuel tank filler cap (9030).
2. Remove fuel system pressure. Refer to fuel system pressure relief below.
3. Locate a quick connect fitting on the return line. The return
line takes fuel from the engine back to the tank. You can find the
return line by following the two lines from the fuel tank forward. The
return line is the one without the filter. Disconnect an accessible
quick connect to open the return line.
NOTE: To remove 5/16 push-connect fittings, use Fuel Line Removal Tool
T90T-9550-B or tool obtained from an auto parts store.
4. Install 3/8 inch ID hose to return line on engine side and route to Rotunda Storage Tank 034-00002 or equivalent
5. Connect ground clamp from storage tank to
vehicle body (This is to prevent static electricity spark--the storage
tank is metal so it is supposed to be grounded. If using a plastic
container skip this step)
6. The fuel pump is equipped with an external
wiring connector near the fuel tank (the pump is inside the tank). The large red wire is pump positive and the large black
wire is pump negative. Unplugging the connector and applying an external 12 volt DC power source to
these pins will activate the fuel pump and drain the tank. (The fuel
pump can also be powered by removing the fuel pump relay and using a
jumper wire to connect the two terminals of the relay socket that mate
with the switch contacts of the relay--these terminals will be attached
to Light Blue/Orange and Dark Green/Yellow wires on the back side of the
fusebox in the engine compartment.)Fuel System Pressure Relief
WARNING: FUEL SUPPLY TUBES ON ALL VEHICLES EQUIPPED WITH
FUEL INJECTED ENGINES WILL REMAIN PRESSURIZED FOR LONG PERIODS OF TIME
AFTER ENGINE SHUTDOWN. FUEL SYSTEM PRESSURE MUST BE RELIEVED PRIOR TO
FUEL SYSTEM SERVICE TO PREVENT POSSIBLE INJURY.
SPECIAL SERVICE TOOL(S) REQUIRED Description Tool Number
Multiport Fuel Injection (MFI) Fuel Pressure Gauge T80L-9974-B
1. Remove air cleaner assembly
2. Connect Multiport Fuel Injection (MFI) Fuel Pressure Gauge
T80L-9974-B to fuel pressure relief valve (in diagram below)
on the fuel injection supply manifold (9F792).
3. Open the manual valve on the Multiport Fuel
Injection (MFI) Fuel Pressure Gauge T80L-9974-B to relieve fuel system
pressure. NOTE: The
tank could be drained through such a tool connection as well if
desired, which would prevent you from having to open a fuel line
connection under the vehicle. A fuel pressure gauge from an auto parts
store could be used as long as it has the drain tube.
[NOTE: The manual says to use a fuel pressure gauge equipped with a
drain hose and a manual valve. This allows for a controlled operation,
but the same thing can be done without the gauge. The relief valve on
the fuel rail is like a valve stem on a tire. When the stem is
depressed, the fuel will spray out. So if you cover the valve with a
towel before depressing the valve, it will catch the spray. It will
only spray for a short time until the pressure is relieved. If you want
to reduce the pressure before depressing the valve so the spray is
less, you can pull the fuel pump relay and start the engine, letting it
run until it stalls. The fuel pressure will be reduced somewhat by the
engine using some of the fuel. Reducing the fuel pressure prevents fuel
from spraying out when the line is disconnected at the fuel filter, but
fuel will still drip out.]