Pontiac Firebird Turbo Installation - Subterranean Turbo System

The fuel pressure-sending unit connects to the driver-side fuel rail. In order to adapt the fuel rails AN-3 fitting to the 1/4-inch NPT fitting on the sending unit, an Aeroquip No. 6 female swivel connector and a NPT pipe adapter were utilized. After using thread sealant tape on the NPT adapter, two 1/2-inch wrenches were used to secure the connections before being fully tightened in a vice. The Schrader valve was removed from the fuel rail, and the Aeroquip connector was tightened using a 1/2-inch wrench.

We connected the gauge wiring harness to the sending unit and then routed it alongside the driver-side valve cover and across the firewall to the area beside the PCM. It was determined that the wires wouldn't reach all the way to the pillar post and would have to be extended. We snipped the harness about 2 feet from the end of the gauge connection and taped the wires to a coat hanger. Removal of the two clips that held the passenger-side underdash trim panel in place followed, as did removing the grommet. Next we pushed the wires through the grommet hole, removed the coat hanger, and routed the wires over to the driver's side.

We then removed the two Phillip's screws along with the two 7mm screws that retain the lower plastic dash panel, and took out the trunk release switch. To access the fuse panel, we reached under the dash and pulled out the two pushpin clips that held the lower dash insulation panel.

After routing the electrical wires that snap into the back of each gauge through the dash area adjacent to the pillar post, we pulled them onto the passenger floorboard. We traced the harness from the fuel-pressure gauge and completed the harness extension by crimping the connections. In this case, crimp connectors with built in heat-shrink were used to form a solid connection.

The headlight dimmer switch was used to power the gauge lights so that they can be varied in intensity on the dimmer switch circuit. To get to the dimmer switch, we lowered the wheel to the down position and pulled back on the dash panel until the six retaining clips came free.

We pulled out the headlight dimmer switch until the wires were visible. Hooking up a test light and turning on the headlights, we probed until we found the power wire that varies in resistance while the dimmer switch is being adjusted. In this case, a green wire provided the power. We connected the power wires that come out of the gauges via a T-tap to the dimmer wire. Then we reinstalled the dash bezel and the plastic cover for the tilt steering column.

The gauge wires were routed to the openings for the gauges. We connected the nylon tubing that provides the boost signal for the vacuum/ boost gauge to the back of the gauge using the supplied 1/8-inch adapter, ferrule, and compression nut. We located the ground wire that comes out of the boost gauge along with the two ground wires for the fuel-pressure gauge and twisted the wires together and connected them to an eye terminal. After crimping the wires, we soldered the connection and then slipped shrink-wrap over them to seal out the elements. With this completed, a hole was drilled into the metal behind the pillar post and the ground wires were attached using a No. 10 self-tapping screw.

The gauges were partially slipped into the pillar pods, and we connected the harnesses and lights. We organized the wires and nylon tubing, using zip ties to ensure a tidy installation. With the wires in place, we had to establish a power source for the fuel-pressure harness. After testing the underdash fuse panel for cranking power, we installed a T-tap. Then we routed the nylon tubing for the boost gauge over to the passenger-side floorboard, where a vacuum T was utilized to tap into the boost signal that was established earlier for the methanol injection system. Finally, we reinstalled the passenger-side trim panel.

To wrap up the installation, we slipped the pillar pod into position, slid the two clips on the front of the pillar trim into the dash, and pushed in the assembly. We reinstalled the two Phillips screws that retain the top of the pillar and then replaced and locked our driver-side T-top. With those two tasks completed, we pushed the gauges in the remainder of the way, after adjusting their orientation to provide a proper viewing angle. We verified proper installation by cycling the ignition key a few times to observe for leaks at the fuel-pressure sender and connections and at the fuel rail, followed by starting the car to see if the gauges operate and illuminate. At idle, the Formula pulled down 18 inches of vacuum and registered 58 psi of fuel pressure. The wires under the dash were then zip tied out of the way, and the lower dash insulation and trim panels were installed. A quick test drive revealed the engine produced 5 psi of boost on the gauge, but more importantly, the fuel pressure was falling to 42 psi under boost.