High Pressure Fuel System on a 65 EFI Fastback

Pressurized Fuel System - EFI of a 65-66 Mustang Fastback

Doing the fuel system in preparation for the EFI was probably the most time consuming part of the process. Not because it was particularly difficult (it's not), but just because it's complete free formed to the car. There are not predesigned parts that I used; every line, bracket, fitting,etc., had to be done from scratch. While time consuming, it was rewarding to get it finished and see the results.

Before starting to install a high pressure, 2 line system in a mustang, the Ford Fuel Injection article written by Ryan McCormick Inject Your Horse - is a must read. This is the article from which my installation was modeled. I used (for the most part) the same components, and it worked perfectly the first time and has continued to do well.

View looking up - filter, LP pump and accumulator. (Click to Enlarge)

Theory of Operation: The diagram above shows the basic fuel flow. Starting at the Supply point from the fuel tank, fuel is drawn out using a low pressure pump (Photo 12) to fill the accumulator tank (Photo 13). The low pressure (approx 7 psi) pump keeps the accumulator tank fuel through a closed loop circuit which returns to the tank. The high pressure pump (Photo 15) running at approx 50 psi, then pulls the fuel from the bottom of the accumulator tank and runs the length of the vehicle to feed the fuel pressure regulator located at the beginning of the injector circuit (Photo 11). This regulator drops the pressure down and maintains it at approx 38 psi to feed the injectors. The return circuit from the pressure regulator to the fuel tank is under minimal pressure. Connecting the return circuit together with the accumlator tank keeps the low pressure side of the system in balance. Both fuel pumps are electrically fed by a 12V supply, as signaled through a relay from the EEC.

Photo 1

Photo 2

Photo 3

Photo 4

Photo 5

Photo 6

Installation: The BC Bronco's fuel accumulator is basically a fuel filter that has been modified for this application. It has the fuel return system added. The unit has a mounting bracket and, due to it's size, shape, and moment, requires a substantial support. Photos 1 and 2 above show the bracing installed along the forward wall of the fuel tank area to support the accumulator tank. A 1"x1" L channel was used on both sides of the forward lip and attached with Grade 8 hardware. The interior angle brace also extends up the trunk sides. Photo 3 shows the mounting bracket for the accumulator tank, as well as the standoff bracket to mount the LP pump. The LP pump is very light, and just required a place holder to take the weight off the hoses and keep it from moving. The LP pump is a Carter P60430 unit, which was < $50 at Advance Auto. (Note in the installation photos, the incoming fuel filter is relocated to closer to the fuel tank outlet.)

Photo 4 shows the routing/connection between the accumulator tank and the high pressure pump. The HP pump needs to be mounted as close to the accumulator as possible. Photo 5 also shows the HP pump. The bracket to mount the HP pump was home made and modeled after the Ron Morris version, by forming and riveting to pieces if sheet metal into a 1/8" thick assembly. Considering the time it took to make it, it would have been cheaper to buy the Ron Morris unit. The HP pump mounts in a cradle for support and vibration dampening. This is a stock HP external pump from a Ford F150 pickup. I picked this unit up off Ebay (Photo 15) for about 40 bucks.


*Photo 7*	*Photo* 8	*Photo* 9	*Photo* 10	*Photo* 11

From the HP pump, a steel 5/16" fuel line is run up over along the rear frame rail and up the passenger side of the car, in this case along the subframe connectors. (Photo 6). without subfames, the lines would mount flush against the floor panels and would have to be secured with adels through the floor. The lines run up the inside of the front frame rail then enter the engine bay behind the passenger kickboard (Photo 7). Care must be taken at this location, being the closest point to the exhaust. The lines were secured at approx 18" intervals with clamps/adels. At this point, the lines exit the bay and are run along the outside of the car. The reason for this is that I could find no way to get the fuel lines to the front of the motor without going over the exhaust system. For safety reasons, I did not want the potential for a fuel leak to run onto a hot exhaust and cause a fire. The lines run outside the car and along the frame rail, and turn to re-enter the car below the battery area. (Photos 8 & 9). From here, fittings turn into the engine bay and have rubber hose barbs to attach the flex fuel line. (Photo 10). Throughout this run, there are line breaks in order to make installation easier. For all line connections, brass fittings and double flare connections were used. It is plumbed in the same manner a brake lines. The fuel lines to the motor are stock Mustang 5.0 fuel rails and rail extensions. The OEM lines were re-bent slightly to clear some modifications, and then attach to the rubber lines using the OEM style fittings (Photos 10 & 11). The fuel rails, fittings, fuel pressure regulator, and injectors are stock Mustang units.

Return line: The 2 steel fuel lines run in parallel through out the system all the way back to the aft frame rail. At that point, the return line is changed to a low pressure rubber line, and it plumbed to tee off and mate with the return port on the accumulator tank. The other end of the tee attaches to the drain port of the fuel tank. Note: I had replaced the tank with a repop tank that was equipped with a drain plug. This made for an easy attachment. (Photo 5). If your tank does not have a drain plug, then the most common alternative is to use a modified fuel sending unit like this one by Ron Morris.

*Photo* 12	*Photo* 13	*Photo* 14	*Photo* 15	*Photo* 16

Electrical Wiring: The EFI power diagram shows the wiring structure for the system. Exerpt associated with the fuel system is shown to the right. The two fuel pumps are wired in series, and fed from the power pin of the FP Relay, through the intertia switch. The intertia switch, shown below, is necessary as a safety measure. It has a gravity/spring loaded switch which can sense inversion, or impact. If the car rolls over, or receives a hard impact, the switch will kill power to the pumps. It is mounted in the trunk in case for sensing of rear collisions.

Pin 22 of the EEC harness feeds the signal line of the relay. This is the computer telling the pumps when to run. Pin 19 from the EEC is the Fuel pump monitoring circuit. This tells the EEC when the FP is actually running.

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