The
fuel management unit (FMU) can be installed at anytime as can a boost-dependent fuel
pressure regulator (FPR). For more info on the differences between these two fuel
regulators, see here. Since both of these work with or without
boost, their installation can be done ahead of time in preparation for the turbo install.
The FMU install is straightforward and rather simple. The first thing that I did was to change the 4AN fittings that were on the FMU to 5/16" barb fittings to accommodate standard fuel line rather than braided. These fittings are available at just about any auto part or home improvement store.
After that, I located a suitable
mounting spot out of the way of turbo plumbing. Right next to the cruise control
unit seemed to be a good place. I drilled out the mounting holes on the FMU to fit
it over the bolt on the cruise control bracket and then attached it to the bracket.
This setup left the right mounting hole open so I used a strip of metal to connect it to the top bolt of the cruise control unit.
Once the FMU is mounted, it is time to locate the fuel return line from the
stock FPR. This is the line that returns the fuel to the tank. The FMU raises
rail fuel pressure by disallowing the fuel to return to the tank. If it cannot be
vented back to the tank, it must go through the injectors.
In order to do this, the FMU must be connected in the return line somewhere between the FPR and the tank. The easiest place to do this is obviously right after the FPR. On the 2.5L, there is a short rubber hose from the FPR to near the throttle body were it connects to a metal line (see photo). This is probably the best place to connect the FMU in line.
After you have removed the line between
the FPR and the metal line, it is time to connect the FMU to them. Connect a fuel
hose from the FPR to the IN port on the FMU. I used the high pressure fuel line
(red) for this since it will see pressure of up to 90psi. Then run a hose from the
FMU OUT to the metal line that the original rubber hose was connected to near the throttle
body. For this, I used standard EFI fuel hose.
Make certain to clamp all hose connections at the FPR, the FMU, and on the
metal line. I suggest band clamps on the high pressure side (FPR--FMU IN).
The OEM spring clamps are OK on the return side.
Once the FMU is permanently mounted in place and all of the fuel lines are connected and clamped down, this is what the setup will look like (below). The only thing left to do is to connect a vacuum line from the manifold to the vacuum fitting on top of the FMU (below/right). Once the manifold becomes pressurized (as opposed to vacuum), the FMU will begin cutting off the return of fuel to the tank. The more the pressure (higher boost), the harder it clamps down and the more gas that is forced to go through the injectors.
Once everything is connected, I would suggest running the car to ensure there are no fuel leaks. If there are, take care of these before proceeding to install the turbo. Things will be tight under the hood once it is on, so it's a good idea to be careful and check things as you go. You will also want to install a fuel pressure gauge either permanently or temporarily to ensure the FMU is working under boost and to tweak the fuel supply.