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GPI G20 Installation Video and Guide


Fueling Requirements

  • This fuel pump is designed, tested and approved for use with gasoline blends (up to E15), diesel fuel blends (up to B20) and kerosene. Please take all due precautions when handling these flammable liquids.
  • Do not use this pump for dispensing any fluids other than those for which it was designed. To do so may damage the pump’s components and will void the warranty.

Power Source Requirements

  • This manual covers 12V (dc) electric gear pump models G20-012PO, G20-012MD, and G20-012AD
  • Do not attempt connection of any pump to a 24V (dc), 115V (ac) or 230V (ac) power source.

Tools Needed

  • Pliers, Slip-Joint Pliers, Adjustable Wrench, Utility Knife, Wire Crimper/Stripper, and Metric Hex Wrenches (Hex Key) (4 & 5 mm – Included)



  • (1) 12V (dc) Fuel Transfer Pump
  • (1) Lockable Nozzle Holder
  • (1) 90-Degree Modular Fitting and hardware kit & (1) thread tape
  • (1) 18 ft. (5.5 m) Power Cord (Attached on models G20-012MD & G20-012AD only)
  • (1) Automatic Diesel Shut-off Nozzle (Model G20-012AD only) or Manual Diesel Shut-off Nozzle (Model G20-012MD only)
  • (1) 14 ft. (4.2 m) Dispensing Hose (Models G20-012MD & G20-012AD only)
  • (1) 15 in. (38 cm) to 40 in. (101 cm) Adjustable Suction Pipe (Models G20-012MD & G20-012AD only)


  • After unpacking the unit, inspect carefully for any damage that may have occurred during transit. Check for loose, missing or damaged parts. Shipping damage claims must be filed with the carrier.
  • Review General Safety Instructions and all Caution, Warning, and Danger statements on page 4 in the G20 owner’s manual.


WARNING: Coverplates protect the operator from moving parts. Never operate the pump without coverplates in place. Never apply electric power to the pump without coverplates in place. Always disconnect power before repairing or servicing.

Mechanical Connections

NOTE: All threaded fuel connections must be sealed with thread tape or a pipe thread sealing compound approved for use with petroleum fuels and tightened securely to prevent leakage.
NOTE: This pump must be mounted on a vented tank.
NOTE: This pump is designed to mount directly to a standard 2 in. male pump tank mount adapter (included).
NOTE: This pump is designed to self-prime with dry gears.
If you require a greater initial prime height, coat the gears with fluid by removing the outlet fitting on the top of the pump and pour a small quantity of motor oil into the gear cavity. Replace and try again. A foot valve with pressure relief may be needed to maintain prime.

Install Tank Adapter and Suction Pipe

  • Wrap lower threaded end of the tank adapter with three or four turns of thread tape (see Figure 2). Using a wrench, tighten the adapter snugly into the fuel tank. NOTE: For Aluminum Tank Installation – To prevent thread galling of aluminum fittings, always prepare the threads for assembly using an anti-seize compound such as Loctite® 567™, Hernon® Dripstop® 940 or equivalent.
  • Using pliers, remove the plastic plug from the inlet port on the bottom of the pump. Place the spin collar gasket into the inlet fitting on the bottom of the pump.
  • Wrap the threaded end of the suction pipe with three or four turns of thread tape (see Figure 3). Thread the suction pipe into the inlet port on the bottom of the pump and hand tighten until snug. NOTE: If your tank is 15” – 24” deep, do not use the included suction pipe extension; if your tank is 24” – 40” deep, attach the suction pipe extension (see Figure 4). The suction pipe will self-adjust to tank depth when the pump is installed.


Install Pump on Tank

  • Clean the tank interior of all dirt and foreign material.
  • Place the pump with suction pipe installed on the tank fitting and tighten securely. Make sure the pump’s spin collar is not cross-threaded.

Install Nozzle Cover

  • Using a 4mm Hex wrench, install nozzle cover using (1) M6-1.0 x 14mm BHCS in the lower hole (see Figure 5). NOTE: For model G20-012PO only, DO NOT install nozzle cover until after power cord has been installed. See Install Power Cord (G20-012PO model) section.

Install 1 in. NPT Outlet Adapter

  • Remove the plastic plug from the outlet port of the pump.
  • Install #222 O-ring into the outlet port. Make sure O-ring is seated properly.
  • Using a 5mm Hex wrench, install the (4) M6-1.0 x 20mm SHCS into the 1 in. NPT outlet adapter in the desired direction on outlet port (see Figure 5).



Install Hose and Nozzle

  • Wrap one end of the dispensing hose with three to four turns of thread tape and thread into outlet port. Tighten securely using an adjustable wrench.
  • Wrap opposite end of the hose with three or four turns of thread tape and thread into the nozzle. Tighten securely using an adjustable wrench.
  • Place the nozzle into the nozzle holder at the end of the pump motor housing. Note that the nozzle cannot be placed in the holder unless the pump switch is OFF.


Install Power Cord (G20-012AD & G20-012MD models)

NOTE: This pump is pre-wired for installation in CLASS I, DIVISION 2 locations such as portable fuel tanks, trailers, etc. The connection method to a battery will depend upon the application.

WARNING: If the pump is to be installed in a CLASS I, DIVISION I location please contact GPI (1-800-835-0113) for the appropriate product.

Install Power Cord (G20-012PO model)

For installation in unclassified areas, the supplied power cord, fuse and strain relief grip may be used.
NOTE: These components have not been evaluated as part of the UL Listed Equipment and are not intended for use in a Hazardous (Classified) Location.

  • To install the power cord, remove the (4) M6-1.0 x 20mm SHCS and electrical coverplate (see Figure 6). If necessary, trim the power cord to the desired length. Strip 3 to 4 inches (7.5 to 10 cm) of outer insulation from the power cord end. Then strip 1/2 inch (1.3 cm) of insulation from the power cord wires.
  • Slide the strain relief grip onto the power cord so that the threaded end of the strain relief grip faces the stripped power wires (see Figure 7).
  • Insert the power cord through the 1/2 inch NPT connection on the back of the pump (see Figure 6). Using wire nuts, connect the black wire to the black wire and the red wire to the red in the pump’s electrical cavity.
  • Position the wires inside the electrical cavity and tighten the strain relief grip securely. Make sure the surfaces are clean. Reinstall the electrical coverplate and switch lever, and tighten securely.


DANGER!: If the pump is to be installed in a Hazardous (Classified) location, it must be installed by a licensed electrician and conform to National Fire Protection Association (NFPA) codes 30 and 70. You as the owner, are responsible for seeing that the installation and operation of your pump comply with NFPA codes as well as any applicable state and local codes. Rigid conduit must be used to install wiring. Note that the lead wires are factory-sealed isolating the motor from the junction box. Failure to follow these wiring instructions may result in death or serious injury from shock, fire or explosion.


Connect to a Power Source

NOTE: Please consult the Owner’s Manual for your vehicle before proceeding.
IMPORTANT: The pump is designed for use with a 12 V (dc) power source. Do not attempt connection of any pump to a 24 V (dc), 115 V (ac) or
230 V (ac) power source.

WARNING: Do not attempt to power the pump from vehicle wiring smaller than 12 gauge, such as the cigarette lighter wire, as these thin wires could overheat and
cause a fire.

IMPORTANT: Verify switch is in OFF position, then route the electrical wires to the source of the vehicle power system. Be sure to support the wires as necessary and protect them from sharp edges, heat or anything that could damage the wires.

  • If the power cord provided is too long, cut to the desired length. Using a utility knife, carefully strip 3 to 4 inches of outer insulation from the end of the power cord. DO NOT CUT INSULATION OF INNER WIRES. Next, using wire strippers, remove 1/4 in. of insulation from the black and red power cord wires.
  • First, disconnect vehicle wiring from the negative ground terminal of the battery, and then connect as follows: Using wire strippers, carefully strip 1/4 in. of insulation from both ends of the fuse assembly wire.
  • Insert one end of the fuse assembly wire into a wire connector (included) and crimp. Insert the red power cord wire into the other end of the wire connector and crimp. Make sure the fuse assembly is positioned outside of hazardous areas and as close to the battery as possible (see Figure 8).
  • Using wire crimpers, attach a terminal post ring (not included) to the other end of the fuse assembly and a terminal post ring to the end of the black power cord wire.
  • Connect the red wire/fuse assembly to the positive side of the battery (see Figure 8).
  • Connect the black power cord wire to the negative side of the battery.

NOTE: Connecting directly to the battery terminal or the end of the battery cable is recommended.

Ready for the next step? For operation instructions and troubleshooting, see the G20 owner’s manual.

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