Fuel Pump Voltage Booster (aka Boost-A-Pump) Part 01
I've always felt the weak link in the fueling system of our platform is the in-tank (or low pressure fuel pump - LPFP). This isn't normally an issue with mild to semi-aggressive builds as the addition of a higher output HPFP and injectors along with an ethanol blend and maybe even some methanol injection have been able to keep up with the majority of the demands of the platform.
However, the reality of it is that no one has
really taken this platform to extremes quite yet. Those extremes include running straight e85 and/or wheel horsepower levels exceeding the 650-700 mark. It's those areas were serious fuel demands come into play and simply installing larger injectors and HPFP just won't do the trick. In order to address this high fuel demand issue, we need to look at the very first step of the fuel system, the in-tank pump. My breakdown of it is that, with those other components, you've basically got yourself a firehose nozzle attached to standard garden hose bib. At the extreme ends of the spectrum, you'll just never be able to feed that nozzle what it needs to truly shine.
I've recently began running straight e85, and already the cracks are starting to show in the armor. According to my tuner, we'd like to see a low pressure side reading of at least 80psi. Well, at WOT, we were seeing dips down into the 60psi range, and the HPFP would follow with a dip in output and/or increase in duty cycle.
Now, I have been preaching that the low-pressure pump is the weak link and to that end, I have explored many, many different options (surge tanks, larger in-tank pumps, etc.). None quite off the table, but most of them are very complex problems to solve and, frankly, exceed my limits of advanced fuel system knowledge. So, to that end, after speaking with Uwe over at XDI who was attempting to install a larger Bosch 400 into a stock fuel bucket I had sent him and found that it just wasn't quite possible reminded me of an old trick that may be able to be revived and used in our platform.
Enter the fuel pump voltage booster, known to many as a Boost-A-Pump, or BAP (although that title is usually in reference to the Kenne Bell version of the device). The theory here is, the more voltage to the pump, the more work it can do. Pretty simple, right? Well, it's a bit more involved than that...so here goes.
The OEM fuel system in our platform is a returnless, pulse-width modulated, direct injection system. What that basically means is, there is a fuel pump driver module (FPDM) that is sending PWM signals to maintain a system pressure that the HPFP can use to push the rail pressures to above the 2000psi mark. It isn't like the old school pumps that just ramp up and down in speed to maintain that pressure, but rather, turn off and on at an incredibly fast rate. This means, you can't simply interrupt the voltage signal going directly to the pump, you need to interrupt the signal pre-FPDM.
So, on the advice of Carl over at
Vapor Worx, I decided to go with the
JMS version instead of the
Kenne Bell or
MSD. The JMS version has a reputation for having the cleanest output signal and has some pretty cool ramp in/out features that I found I'd like to use as well as being able utilize a 0-5vdc trigger if required.
It all began with the arrival of the pump:
It comes with everything you need to get this thing up and running. That includes a Hobbs switch for using boost as a reference if you are so inclined...
However, I really wanted to utilize the 0-5vdc trigger feature of this device as it allows you to fine tune a ramp in/out rate if you desire (and I do). So where do I get a 0-5vdc reference? Hmmmmm...well, you really DON'T want to tap into the MAP sensor signal as the act of tapping it can sometimes introduce noise into the system and have weird effects on the vehicle. You also don't want to tap into the Throttle Position Sensor (TPS) as that can open and close at various positions not equating to actual fuel demand. I guess I could install a second, dedicated MAP sensor, but that would be over-engineering the solution. Why not just go with a solution that JMS already had in-place. Use of the accelerator pedal position (APP) sensor. Because I like plug-n-play, along with the ability to "EDIT/UNDO", I opted for an
off-the-shelf solution from JMS. They had a Ford wire harness for purchase:
But if you want to keep it on a budget and not purchase the adapter harness, simply splice into wire #2...
...of the connector C2040:
The accelerator pedal connection before installation:
After installation:
Since I was going to use the pedal position as my 0-5vdc reference, I had to see what the actual range of output was. Just because it is a 0-5vdc output doesn't mean it's at that exact range. Below is a photo of the voltage at rest (left) and the voltage value when the pedal is floored, simulating WOT (right):
This test was done key-on, engine-off.
Next was accessing the FPDM. Even though it is underneath the c-pillar cover, because of the way Ford decided to assemble this car, you have to remove almost the entire rear interior, lol....ugh.....
Here is everything off but placed loosely back into position, other than the c-pillar cover:
It was at this point that I did some data collection on what the FPDM is seeing. I have two Fluke meters so I decided to also see how that voltage compares to what the pedal sensor is putting out. Here's a video compilation:
I have plans to wire this in such a way that I can remove the BAP and put it back to stock relatively easily. This requires the use of my extensive Deutsch connector set:
Here is the JMS "wiring" guide and which wire is needed to be intercepted:
And here is the OEM wiring schematic along with connector C3239 pinout, the wire of concern here is wire #1:
Tape peeled back and power wire exposed (Purple/Green Stripe...Incredible Hulk colors, how appropriate for the POWAH wire, LOL):
Using a specific Deutsch crimper...
...you can make these male/female ferrule crimps:
One side done. Just one wire from the FPDM to this connector:
Other side done. As you can see it has 2 wires, one going to an existing ground. When it's connected in OEM configuration, it goes nowhere, but when it is connected in BAP configuration, it will be the ground for the BAP wire.
And here it is in full OEM configuration. I can easily connect/disconnect as needed:
Now onto the BAP connector itself. The wires are just cut wild when you get it from JMS, but I took a page out of the MSD book and used a DTP Deutsch connector end here as well:
