With the VMP blower supplying us with a significant amount of power, we knew that the factory fuel system would need a little pick-me-up. JMS Chip & Performance supplied us with a PowerMax fuel pump voltage booster/regulator (PN PM-1000, $329). Ford equipped the '03-'04 Cobras with a dual pump assembly set to run on a constant 12 volts when in use, but we still needed to increase fuel output with the new TVS installed. The booster/regulator from JMS allowed us to still utilize the factory pumps, but increase the voltage from 12 to 18 volts. With it installed, the minimum amount of voltage the pumps are receiving is now 14, and with the increase in voltage, the factory pumps can now deliver more fuel at higher pressure.
The PowerMax will work on any Mustang and is designed to increase the stock fuel pump's capabilities by over 80 percent. Included in the JMS kit is a remote-mounted voltage control knob and Hobbs switch. The Hobbs switch is activated when it sees a predetermined amount of boost. It is preset at 5 psi, but is user-adjustable from 3 to 7 pounds. We opted to keep the pre-setting, so when the new TVS blower produces 5 pounds of boost, the Hobbs switch activates the booster/regulator and voltage is increased.
The voltage control knob works hand-in-hand with the Hobbs switch and allows the user to set the voltage increase over a specific period of time. There are four settings on the voltage knob--0-, 0.25-, 0.50-, and 0.75-seconds. For our install, we set the voltage to increase over a half a second. What this is doing is avoiding a fuel spike when going to WOT. The pumps are starting at 14 volts and gradually increasing to 18 volts over the half a second time frame. We not only needed a better supply of fuel from the fuel pump, but the fuel injectors as well. We called upon our good friends over at Central Florida Motorsports where they supplied us with a new set of Siemen 60 lb/hr injectors. With the PowerMax and larger injectors, our '03 Cobra now has more than enough fuel to handle the added boost from the TVS.