on3 fuel hat wireing

[Dylan]

Hey guys,
in the process of putting a turbo on my 06 mustang gt and am at the point of installing the fuel pumps. I went with the on3 triple billet fuel hat with 2 320 lph pumps. my issue is I dont know how to wire these up to the signal wire coming from the fpdm that tells the pumps how hard they need to be working. ive been searching for days and all I have found is that this signal wire is also a ground but there are a couple grounds going into the stock fuel hat one going to the bottom on the fuel level sender and one on the pump itself. Im guessing its the ground on the pump and so can I just make a y off that ground to my two new pumps. Im also unaware what wire controls the fuel level sender and haven't found any pinouts for it. all the wires in the hat are tan/brown or black and outside it there multiple colors so its hard to trace. if anyone has a pinout or some experience on this topic anything is appreciated
Thanks!

 

[JeremyH]

First a disclaimer about the poor quality of the fuel pumps, that out of the way, did you just get the hat with the 2 pumps? That config is intended for a return setup with feed, regulator and return line. Its too much pump to be run on any stock wiring or the oem fpdm anyway. So which way are you trying to use it? That will determine what needs done and where to go from here.

 

[Dylan]

First a disclaimer about the poor quality of the fuel pumps, that out of the way, did you just get the hat with the 2 pumps? That config is intended for a return setup with feed, regulator and return line. Its too much pump to be run on any stock wiring or the oem fpdm anyway. So which way are you trying to use it? That will determine what needs done and where to go from here.

I have a 2 relay setup, power coming off the battery powering the pumps with a 40amp inline fuse. The relays have power ground and signal wires. I was hopeing i could run signal wire to the fpdm to control the dury cycle and run power to battery to make sure I dont blow the oem harness. Is this impossible to do? Im only looking for 480hp range but am running e85 so need a good ammount of fuel.

 

[JeremyH]

Yeah it cant work like that. The frequencies the fpdm operates at far exceeds what the a relay can handle. The relay will simpley use the normal power in wire to the fpdm (inertia wire) as the trigger for the relay so at key on the relay(s) switches and supplies power from your battery power wire directly to the pumps and they will run full on. So you are setup for return correct? The fpdm will not be used anymore with a return system.

 

[Dylan]

No im setup returnless :/ does this mean I either need to go returnless or find a new pump setup? I was assuming that there was a way to tap into the signal wire on the fpdm to control the fuel pumps

 

[JeremyH]

So the fpdm gets its signal from the pcm based on the readings it get from the frps which measure fuel rail pressure and temperature. The fpdm just modulates voltage to the fuel pump to adjust its speed/flow rate to maintain desired pressure at the rails. The pcm has two wires going to the fpdm a monitor and control wire. The fpdm get power in on the inertia wire and then has a chassis ground wire. Then a power and ground wire out to the fuel pump. The fpdm uses high frequency ground switching (pulse width modulation) to adjust the effective output voltage to the fuel pump.

The way you would upgrade wiring to the fpdm so it can handle a larger pump would be taking that normal power wire (inertia wire) cutting it and using it to trigger a relay and then have the relay feed power from the battery on a thicker 10awg wire back into the fpdm power input. However this single fpdm setup is not adequate to run these 2 320lph pumps. The fpdm has thermal protection and will shut down from excess current draw.

There is a way to run those 2 pumps in returnless but you will need two fpdms and a dual fpdm wiring lilke the gt500 fuel setup. I will attach some diagrams so you can see how that works.

What is the full setup and what kind of power are you trying to support?

 

[JeremyH]

This is the dual fpdm wiring schematic from the gt500 with relay to feed power to each fpdm.

 

[JeremyH]

If you converted to return system where pumps are run full on and pressure is maintained by a mechanical fuel pressure regulator and excess fuel is returned to the fuel tank it would be wired like this not using the fpdm anymore. (the hobbs switch is optional for if you don't want to run both pumps full on all the time)

 

[Dylan]

Thanks for all the info. Im running a on3 kit with 70mm turbo using 2 320lph pumps with 60lb dekka injectors and running e85 trying to get close but stay under 500hp guess i didnt do enough research on my fuel system before hand. I have an idea but my tuner isnt likeing it so far but i dont see the issue with it. I was thinking of running these pumps on a return system but using a gm fuel filter that doubles as a fuel regulator with a return line. My tuner dosnt like it due to the fact it dosnt have boost reference but I cant see that being that big of an issue. It operates at 58psi rather then fords 43.5 so some adjustments would have to be made but seems like a quick cheap and good fix to the issue.

 

[JeremyH]

Thanks for all the info. Im running a on3 kit with 70mm turbo using 2 320lph pumps with 60lb dekka injectors and running e85 trying to get close but stay under 500hp guess i didnt do enough research on my fuel system before hand. I have an idea but my tuner isnt likeing it so far but i dont see the issue with it. I was thinking of running these pumps on a return system but using a gm fuel filter that doubles as a fuel regulator with a return line. My tuner dosnt like it due to the fact it dosnt have boost reference but I cant see that being that big of an issue. It operates at 58psi rather then fords 43.5 so some adjustments would have to be made but seems like a quick cheap and good fix to the issue.

That fuel filter "regulator" restrictor indeed is not idea for a boosted setup. I would agree with your tuner as well and not recommend that. The corvettes that originally used those gm filter pressure restrictors had a 255lph fuel pump iirc. Your almost tripling that flow rate with this pump setup. Meaning pressure pre-filter may be really high causing the pumps to wear out really quick.

Also ford used 39.15 psi as its delta up until 2011 when the coyote came out with its mechanical returnless setup and internal 4 bar regulator on the fuel hats. GM used 43.5.

It indeed would be an initially cheap way to go. I do not see that setup working out for you for very long on a turbo e85 setup.

 

[Dylan]

So i may just run a second fpdm. This would then do away with my relays correct. Would the new fpdm need to be wired into the pcm or how would that work. What all do i need hardware wise? I found a fpdm for 45 on ebay but uncirtin the harnesses and connectors i would need from there? Any info is appriciated

 

[JeremyH]

Traditionally you would need a special dual harness that the frpp fuel kits comes with. It is possible to wire one yourself if you have the know how and just mimic the diagram which is what I do. It still uses a relay for upgraded power feed, up at the top center is a 4 pin relay. The second fpdm mirrors or mimics the primary essentially so you need to splice from the first fpdm's pcm control signal wire into the second (yellow wire to pin 6 on the diagram). If you notice you don't need to do it with the pcm monitor wire so the second fpdm will not need anything run to that pin. Each fpdm gets power in from the relay and a chassis ground. Then power and ground outputs from each fpdm to its respective pump. The pin out definitions are at the bottom of the pic. So that diagram has everything you need to do it.

You will want a fpdm plug to make it easier and more reliable to install the second fpdm which is what I do. Motorcraft sells the fpdm plug pigtail the part number is WPT-903. Here it is on amazon.

Amazon.com: Motorcraft WPT-903 Pigtail: Automotive

 

[Dylan]

If i go with the gm regulator and ran a hobbs switch would that be a decent way to go or still a bad route to take?

 

[46addict]

For <500hp your 60lb injectors and a Walbro 405 should do the job. You can wire in the pump to the stock hat or buy their drop in version. The S&H drop in Walbro kit will be better than what you get at LMR or some other parts vendor because they sell a true 400-405lph pump. And they will include a wiring upgrade kit for next to nothing. Stay returnless and keep it simple.

 

[JeremyH]

If i go with the gm regulator and ran a hobbs switch would that be a decent way to go or still a bad route to take?

I would say its a bad idea for anything other than a built na setup.

If you stay returnless with the dual fpdm setup you wont need any regulator, or larger single pump option in the oem hat liked mentioned.

 

[Wes06]

Using that gm regulator under boost your relative fuel pressure would drop without a means to raise it to counter the boost in the intake manifold.

Do it the correct way. Or stick with the stock returnless setup

 

[Dylan]

What im gona end up doing is run the gm regulator with a hobbs switch because i have them laying around and then over the winter Im gona start sourcing a full return system togather but try and find some deals on it so im not spending $600 to go return. I have plans of building motor in the coming years so will just get a head start on fuel system. Thanks all for your imput. Just cant justify the headach of wiring in an additional fpdm with all the tweaks it would require when car wont see more then 10k miles before it gets a forged 4.6 or mabe 5.4

 

[Wes06]

I still agree with your tuner and Jeremy. Not having boost reference to the regulator will cause effective pressure in the line to drop when boost goes up. Which will then lean you out