Holley pro-jection 2D Installation And Troubleshooting Manual - page 12
2. Start by cutting two sections of 3/8" fuel hose. One piece goes form the pump outlet to the filter and the other from the filter of
the TBI inlet. Be sure the arrow on the filter indicating flow direction.
3. Push the hoses onto the filter all the way until they contact the filter body. Secure the hoses with clamps.
4. Connect the free ends of the hoses to the TBI inlet and the Pump outlet and secure with hose clamps.
5. Conveniently mount the filter using the fuel filter clamp.
6. Use the existing boat fuel filter or a OMC
filter kit part number 174176 or equivalent. The purpose of this filter is to protect
the fuel pump from particles of dirt or other foreign material. The filter should be installed with the arrow on the filter pointing
in the direction of the fuel flow. Secure the ends of the fuel lines with U.S.C.G. approved hose clamps.
8.6 Return Line Installation
The Holley digital PRO-JECTION System requires a return fuel line to the fuel tank so that unused fuel can be routed from the
throttle body. There are two methods of installing a return line on a boat. The preferred method is to run a hose or line from the
throttle body outlet back to the fuel tank. This can be done only if the return line fittings are already on the fuel tank. If a return
line does not currently exist on the boat, the user may want to remove the fuel tank and modify it with an additional fitting of 1/4”
I.D. minimum. The tank should be cleaned if removed and modified. The other method is used when there is no access to the
tank. The return line must then be routed from the throttle body outlet back to the inlet side of the electric fuel pump. A
minimum size of 1/4” I.D. is recommended for the return fuel line. Determine if the fuel system return lines will be routed using a
return to the fuel tank system, or a return to the inlet side of fuel pump system. See Figure 6 for a diagram of the two fuel
system configurations. Once a determination has been made, go to the section below required for your installation and follow
the installation steps.
DANGER! ALL FUEL LINES MUST BE U.S.C.G. APPROVED. METALLIC LINES MUST BE MADE OF SEAMLESS
ANNEALED COPPER, STAINLESS STEEL, NICKEL COPPER, OR COPPER NICKEL AND EXCEPT FOR
CORRUGATED FLEXIBLE LINE, HAVE A MINIMUM WALL THICKNESS OF .029 INCHES. RUBBER HOSE
MUST BE MARKED “U.S.C.G. TYPE A1”. UNITED STATES COAST GUARD APPROVED HOSE CLAMPS
MUST ALSO BE USED. USE OF AUTOMOTIVE GRADE FUEL LINES COULD CAUSE A FIRE OR EXPLOSION
HAZARD WHICH COULD CAUSE PROPERTY DAMAGE, SERIOUS INJURY, AND/OR DEATH.
WARNING! Use only approved fuel lines. Follow all U.S.C.G. rules and regulations. The return fuel line should enter
the fuel tank at the “fuel level sending unit flange” or at the “filler neck”. The filler neck or sending unit
must be removed from the tank to perform this operation.
DANGER! PROPER INSTALLATION OF THE FUEL RETURN LINE MAY NECESSITATE COMPLETE REMOVAL OF THE
FUEL TANK. THIS WORK SHOULD BE DONE BY A FUEL TANK SPECIALIST, WHO HAS BEEN TRAINED IN
THIS WORK AND IS FAMILIAR WITH SAFETY REGULATIONS AND PRECAUTIONS NECESSARY TO DO
THIS WORK. IF A PERSON ATTEMPTS THIS WORK WHO IS NOT FAMILIAR WITH THE SAFETY
REGULATIONS AND PRECAUTIONS, AN EXPLOSION HAZARD MAY RESULT IN PROPERTY DAMAGE,
SERIOUS INJURY, AND/OR DEATH.
NOTE: Anchor all fuel lines securely at 1-½ foot intervals. The use of U.S.C.G. approved fuel line tubing will afford maximum
fuel line protection against premature wearing due to flexing, temperature extremes, salt water, weather, etc.
Attach a section of 5/16" hose to the outlet of the throttle body and secure with a hose clamp. Run the other end to either the
fuel tank (Method 1) or the inlet of the pump at the T-fitting as previously discussed in earlier text (Method 2). Secure with
clamps.
NOTE: 1/4” U.S.C.G. approved hose is included with the kit, should it be required for specific applications.