I declined to purchase the Kenne Bell Boost-A-Pump which basically increases the voltage to the stock fuel pump thereby increasing it's flow.  This occurs at either WOT for naturally aspirated motors or at 3.5psi of boost depending on which model you buy.   Since I had already installed a 190lph in tank Walbro unit, I didn't need to up the voltage for more flow, which IMHO is a cheesy way to increase fuel pump output.  I wasn't too keen on the BAP's set 3.5psi ON/OFF boost reference either. 

According to a Super Ford Magazine article on the BAP, the stock 88lph pump would be upped to 132lph with the BAP.  Not bad, but still substantially lower than the 190lph I have now.  FYI, the 190lph pump I have now can be upped to 285lph with the BAP which of course is nothing I would ever use.  The only thing that I could see nice about this unit is that you can vary the fuel pump voltage from a dash mounted knob.  This would make fine tuning fuel pressure and the A/F ratio a snap.  But for the $199 MSRP, I'll stick to tuning the hard way, especially in light of the fact the Walbro 190lph pump was only $82 in the bulk buy.

So, I have the volume covered, but I needed something to control fuel pressure with reference to boost.  There are basically two ways to do this; a boost-dependent fuel pressure regulator (FPR) or a fuel management unit (FMU).  A boost dependent FPR takes the place of the OEM FPR, but is adjustable and can be referenced to a pressurized manifold as opposed to a vacuum-0psi manifold pressure (naturally aspirated).  This can be a great item for tweaking, but they are more expensive and leave much room for improper tuning.  Since the OEM FPR is connected directly to the fuel rails on the 2.5L, the FPR must be located elsewhere and connected to the rail and return line with (preferably) braided hoses.  Toss the OEM FPR on the desk for a paper weight when you're done.

I opted for the FMU instead of the FPR basically for ease of installation and cost.   I purchased a Vortech 12:1 FMU (P/N 6Z110-111) directly from Vortech.  Price was $184.95, but you can purchase these from Summit Racing for $148.00.  Summit had a 2 week back order on them so I went straight to Vortech.  As I was saying about the price difference between the FPR and FMU, the boost-dependent FPRs will run anywhere from $200-$300 depending on the brand, adjustability, and features.

The FMU is also much easier to install than the FPR because it works in conjunction with the OEM FPR.  The FMU is simply placed inline with the return hose to the tank.   A vacuum line is then connected to the manifold to detect the pressure (boost).   It is important to note at this point that FMUs only work under boost. From vacuum to 0psi, the OEM FPR does it's job.

FMUs are rated by how much fuel pressure they increase per pound of boost.  For example, a 12:1 FMU raises fuel pressure 12psi for every pound of boost.  A 10:1 raises it 10psi/1psi of boost.  Vortech makes 12:1, 10:1, 8:1, 6:1, and 4:1 FMUs.   Vortech also makes a very nice "Super FMU".  This FMU is fully adjustable as per the slope of the fuel pressure increase, minimum/maximum pressure, and several other settings. This can be used as a standalone regulator or as a normal FMU. Price is rather steep at $299.95. At this time, I should say that Cartech (aka as BEGI) also makes an adjustable FMU (from 10:1-1.5:1). These would really ease the tuning process, but when I asked John about it, he said that he hasn't had much success with the newer versions of the Cartech FMUs.

A little calculation needs to be done to get the actual fuel pressure on the car.  The equation looks like this: 50% static FP + (12 x boost psi)=fuel pressure.  This equation is for a 12:1 FMU.  A 10:1 would replace 10 for the 12, 8:1 would have an 8 in place of the 12, and so on.  Since 50% of the vacuum is going by the OEM FPR, you only add one-half of the static (idle) fuel pressure to what the FMU is doing.  This is straight from Vortech Tech Support.  This is what it would look like graphically for the 12, 10, and 8:1 units.

As you may notice, the 12:1 FMU will probably cause enough fuel pressure to force the injectors to go static somewhere around 5-6psi.  I had originally planned on purchasing a 10:1 FMU, but John talked me into the 12:1.  He said it is always better to be more rich than lean for safety purposes.  What will happen here is that we will bleed off some vacuum to tune the 12:1 down to a 10 or 8:1.  This is common practice as everyone I have talked to with aftermarket turbo kits are doing the same thing.  Vortech mentions this on their site as a way of tuning it and even sell recalibration kits to do it.  The 10:1 is probably rich enough and could possibly be bled off a little for anything over 6 or 7 psi.  Tuning the car is John's job so I won't know exactly where it will be running until everything is on the car and functioning. 

OK, here are the photos of it.  Exciting stuff, huh?!  Yes, right out of the box, the top (right) has scratches on it.  What do you want for $185? The fitting on the top is for the reference line that goes to the manifold.

Below, right is a photo of the side.  The fitting directly in the middle is the OUT, flowing fuel back to the tank.  The 90° fitting on the right is thus the IN.   After fuel leaves the OEM FPR, it heads into the FMU there.  The higher the boost, the tighter the FMU closes the return line, forcing the fuel to go through the injectors instead of back to the tank.

Be sure to check back after the install to read about how it's working and how we've tuned it!

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