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Discussion Starter · #1 · (Edited)
So after running my DW300 in-tank pumps for a year or so, I started tweaking pump voltage through the FPCM and quickly fried the FPCM itself. I have read elsewhere that the OEM module also drives the second pump at a lower voltage, as the FPCM itself is ultimately limited in the voltage (and amperes) it can handle over time. Like any circuit, more amps over time will shorten its life and it reduces your total potential fuel flow.

One option, to fully maximize the DW300 in-tank pumps, is to split the current between the FPCM itself and a second driver - enter the Vaporworx Ally controller. It's pretty slick, as it emulates the OEM FPCM signal for pump pulse-width modulation to drive the second pump as if both were still controlled by the OEM module, but it can handle 40 amps itself. So you're effectively cutting the current draw through the OEM module by half (as it's only driving one of the in-tank pumps, and the Vaporworx module carries the second pump).

In other words, you can think of the Vaporworx module as a stand-alone relay that mirrors the signal from the FPCM, but Carl (of Vaporworx) has built them to handle way more current than any in-tank pump can draw, and in this setup the life expectancy of his modules is 90+ thousand miles give or take.

Running the wires in a suitable manner is the hardest part of this install, but the whole think took me about 5 hours due to cutting, splicing and running conduit under the car and fishing it up to the fuel hat (see below).

Vaporworx Ally controller (website)

The controller is simple: +12V and Neg to the battery terminals, +12 and Neg to either of the in-tank pumps, pinning them into the connector at the top of the fuel hat, and a signal wire either of the Neg pump wires (for the PWM signal). There is an option to wire in a BAP also, but it's probably not needed for our cars in this scenario.

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Easy option: run your +/- wires to the pump connector along the side of the trunk under the rear seats to your cut-out (because you have cut out an access panel by now surely). But your wires will be exposed under the rear seat and where they drop down to the fuel hat, so I don't recommend this.

Hard option: run your wires through the grommet in the battery compartment, which drops down to the passenger rear quarter panel behind the rear subframe. From here, you can snake them over the subframe to the gas tank and fish them up to the fuel hat and pump connector. This takes a while, but is easily done with a flashlight, a few jack stands and some patience.

I just punched a hole in the grommet (it's very thin, but pliable) and taped the Pos/Neg and signal wires together. Push them through and find them by pulling back the rear wheel well cover. Pull out about 6 feet of wire, then wrap them in sheathing.
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It was hard to get photos here, but using the OEM harnesses under the car you can fish them over the rear suspension and rear subframe, using zip ties as needed, and then work the wires to the tank. I dropped a spare wire from the top of the tank down, taped it to the bundled wires and then pulled it back up to the fuel hat:

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Now you need to strip the three wires and install the provided terminals with a good crimp. I de-pinned one channel (a gray and red wire), and replaced them with the red/black (Pos/Neg) wires I just pulled up. Note: the two sets of wires that control the pumps are Tee'd off from a single Pos/Neg feed from the FPCM, so it doesn't matter which side you use. The third, gray wire is the PWM signal and can be connected to the gray (neg) wire you just de-pinned, as it is still receiving the signal from the FPCM; I used a spare GT280 connector I had laying around but it could be crimped, soldered or whatever.

The remaining red +12V wire needs to be terminated safely to avoid shorting - I used a few layers of heat-shrink to cover the exposed terminal, while allowing me to re-install it down the roead if needed.

Hood Car Vehicle Motor vehicle Automotive fuel system


Then connect the Vaporworx controller using the supplied terminals and the wires you just ran:

+/- to one of the in-tank pumps (red/black)
+ to the Positive Battery terminal (orange, fused)
Gray PWM signal to the de-pinned gray wire from the fuel pump connector (at the fuel hat)
Neg (black) to the battery ground into the chassis just to the rear of the battery

Vehicle Automotive tire Hood Motor vehicle Automotive lighting


Car starts right up and functions normally with both pumps running, however the total current draw is now split between the OEM FPCM and the Vaporworx controller. Overall it's very clean and I expect it to be durable. The OEM FPCM is still probably not going to like more than 15 volts, but since the DW300s can pull 14-15 amps each (at 13.5 volts!) with higher line pressure, this mod should allow me to exploit their full potential with higher PSI without frying another FPCM.

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The cool part is Vaporworx has several different controllers, so I picked up a second one from a forum member that is MAP-triggered (3 pis but you can choose higher pressures if desired). So I will be replacing my Dsteck module with that, to drive my external Auxillary pump off the second Vaporworx controller - so that all three pumps are pulse-width controlled and hopefully I'll be able to reduce some of the fuel pressure spikes that happen when the Auxillary pump kicks on.

This controller is similar, but has three wires: the orange/green are +/- to the MAP sensor in the blower, and the gray wire is again the PWM signal that piggy backs off the same gray wire as the first controller. So both controllers will be in the trunk, with just the power and signal wires running up to the front of the car. That install will come later.
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Caveat: this is just ONE option. I still have to experiment with tuning the pump duty cycles and voltages to reduce the fuel pressure spikes and pump modulation that happens with the OEM module - because it is still in control! But, after frying one FPCM and having to replace it, I found this to be an interesting and promising option for our cars since so many of us are running aftermarket in-tank pumps and Aux pump kits.

Many people would rather go to a return-system and skip all this stuff. But my car is more of a hobby than a specific goal, and it's a fun challenge to try out different options. I've never heard of Vaporworx before Adam112 told me about them, and Carl (of Vaporworx) makes quality stuff. He also answers his phone pretty much 24-7 and will talk your ears off with advice, explanations and talking over your build I found him to be a really nice guy to talk to and very helpful - so I wanted to give him a special plug here.

Definitely check out his website for any fuel control needs you have.
 

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Carl is indeed top notch. Glad y’all are acquainted’

And cheers to a more robust setup.
 

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Discussion Starter · #6 ·
Thanks guys - credit to Adam for knowing more than I do and to Carl for truly being a remarkably savy guy with these things.

That flow vs pressure graph is telling on the DWs. Something to keep in mind as that's how I popped my FPCM the last time commanding 80+ psi line pressure. :D

I'm glad Adianity built this motor right - because I beat the piss out of it with all of my test and tune stuff.


Ironically, the OEM FPCM still seems to like to pull line pressure under load in certain situations, but it is definitely a tune issue. I will have to experiment further and report back.



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Awesome!

After swapping my tank and hat, I think I’ve figured out I have a dying or dead stock pump so this is in the near future for me. I really don’t need more fuel than stock pumps can supply, but $1000 for a new GM pump assembly is ridiculous.
I was concerned about burning up the fpcm with dw pumps. But this seems to be a great fix that keeps the system as close to stock operating as possible.
 

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Glad to see you continue to push the stock fpcm system as far as you have.
I'm also glad I found the one member to unload that controller on, lol.
Like RedTXV said, your detailed write-ups are nice to follow.
And lastly, Carl's customer service is top notch, I don't think he sleeps very much because he will respond after midnight on occasion.
 

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Now you need to strip the three wires and install the provided terminals with a good crimp. I de-pinned one channel (a gray and red wire), and replaced them with the red/black (Pos/Neg) wires I just pulled up. Note: the two sets of wires that control the pumps are Tee'd off from a single Pos/Neg feed from the FPCM, so it doesn't matter which side you use. The third, gray wire is the PWM signal and can be connected to the gray (neg) wire you just de-pinned, as it is still receiving the signal from the FPCM; I used a spare GT280 connector I had laying around but it could be crimped, soldered or whatever.

The remaining red +12V wire needs to be terminated safely to avoid shorting - I used a few layers of heat-shrink to cover the exposed terminal, while allowing me to re-install it down the roead if needed.

View attachment 153837

Then connect the Vaporworx controller using the supplied terminals and the wires you just ran:

+/- to one of the in-tank pumps (red/black)
+ to the Positive Battery terminal (orange, fused)
Gray PWM signal to the de-pinned gray wire from the fuel pump connector (at the fuel hat)
Neg (black) to the battery ground into the chassis just to the rear of the battery

I assume you have this up and running, maybe I'm not understanding how this thing is wired. I had this stuff backwards when I first put my hat on. Not the best color strategy imo.

The pink and pink/blk are the ground side or pwm'ed side of the pump, Grey and grey/blk are the +12. Shouldn't the pink from the factory harness be the signal to the vaporworx unit and you'd cap off the unused grey (+12V)

Here's a schematic I found in another thread, supposedly for a 2010, but I would assume it's the same wire colors for all years.
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I think this diagram is for the LT cars. Maybe their +12 is switched for the pwm signal. Or his controller is looking a pulses on the +12 side to operate the controller. If so, then at least in your picture, it looks like you have your second pump wired backwards. FYI, the pump will still "run" backwards it just won't pump any fuel.

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I think it was said in another thread and in Random's original post that the - side of the fpcm is the pwm side. Maybe that's not correct. I'm no Electrical Engineer, I just want to understand what's going on.
 

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Discussion Starter · #14 ·
So a couple of things:

First, Adam used the wrong wire colors when he made the fuel hat (it was one of the first ones IIRC?). In either case, the circuits are correct, he just mixed up the red/black colors on that specific part of the pigtail. Crafted by hand with love, these things happen. :) I previously confirmed this with the fuel hat out when I was diagnosing some FPCM issues a while back.

Secondly, because current is ultimately electrons moving through material from the negative to the positive (low to high potential), I'm GUESSING that's why you need the negative terminal for PWM, much like why you take the negative battery terminal off first? Fuck if I know - other than Carl said to use the gray wire, so I USED THE GRAY FUCKING WIRE! Muhahaha. The diagram posted above is correct, the gray (negative) wires from the FPCM are signal.

Lastly, the fuel pump connector (from the FPCM to the tank) is ( + - - + ), with the two +12v wires being outer-most as shown.
 

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Discussion Starter · #15 · (Edited)
I assume you have this up and running, maybe I'm not understanding how this thing is wired. I had this stuff backwards when I first put my hat on. Not the best color strategy imo.

The pink and pink/blk are the ground side or pwm'ed side of the pump, Grey and grey/blk are the +12. Shouldn't the pink from the factory harness be the signal to the vaporworx unit and you'd cap off the unused grey (+12V)

Here's a schematic I found in another thread, supposedly for a 2010, but I would assume it's the same wire colors for all years.
View attachment 153843
The schematic is correct. Electrons flow from the (-) terminal, which is why you always unhook the negative terminal from the battery first: if you block the flow of electrons, it doesn't matter how grounded (+) you are if you're holding the low potential (+) side of the battery. The (+) terminal is actually ground as it is relatively positively charged (low potential) compared to the battery as a store of a bunch of angry (-) electrons looking for somewhere to go. A google search tells me that since current was discovered before we actually knew about electrons, the assumption was that "power" came from the positive terminal and thus our terminology has evolved around that basic, incorrect assumption from back in the day. So you have a bunch of shit about current and potential and all that, but it's ultimately just seeing which end of the circuit has the most electrons and determining the potential of them wanting to get to the other end of that circuit.

Kind of like saying East and West while you're on a sphere rotating around your point of reference in multiple plains. It still works at a basic level, but isn't really correct.

At least, that's what I think and I'm sticking to it! :D Oh, and most importantly... the car runs so...
 

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I showed this to a couple of the EE nerds here at work and they confirmed that this switch symbol (highlighted) would indicate that it's a switch +12v signal and ground is always closed. I got a more in depth reasoning of using switched + side that I won't bore anyone with.

So the grey and grey/blk are switched +12v and pink and pink/blk are ground.

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Discussion Starter · #18 ·
It's the gray wire, dammit! lol

That's all I know. Well, that - and apparently the DW 300 pumps work really well spinning backwards. 😄
 

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Discussion Starter · #19 ·
While we're all here...

Vaporworx tells me the Walbro (TI) GSL 392 aux pump is PWM compatible - anyone have a different experience?

I think I understand how to adjust the pump DC relative to line pressure in the FPCM, but it's futile when the external pump kicks on at 7psi and gives my rails the full beans! So I am going to move forward with trying to PWM the external pump.

The easy answer here is to just pull the tank and put in a ZR1 pressure relief. But still... maybe I want to run 80 psi in the future?
 
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