GT350 Dual Pump in 2015 Mustang GT

[engineermike]

@96gt4.6 I completely agree with you on many points. However, I think I would have tried lowering the "low" duty cycle before giving up on the dual pumps. Another option would be to change the inferred rail pressure vs flow, as this pressure is used to modify the injector flow rate it expects to get.

I'm working on something similar, but to run the GT500 bucket off of a pair of FPDMs in a gen3. I'd like to know more about your wiring setup. Also, I have the GT500 fuel line with filter ready to go, but not 100% certain it's the same size fitting at the firewall or if I'll need to drop the tank to swap the line out. I'd appreciate your feedback on this.

As for the DW400's abilities to run E85, I'm actually doing that now. I'm running a DW400 (with check valve) on a BAP at 18 volts. I've been able to support 680 lb/hr of fuel flow with pressure dropping to about 52 psi. This is good enough to support a Gen V whipple on the 3.25 pulley at .77 lambda in 80 deg weather, but it won't be enough in colder weather or if COT kicks in. I do understand the centrifs with stock fuel rails can't take the DW400 this far, though.

Sponsored

 

[NightmareMoon]

I'm getting pretty interested in running dual pumps in my '16 GT (to address fuel starve under high G loads in left sweepers). Is the fuel pressure the unsolvable issue?

Any other ideas to get a fuel pickup in each tank? Do I just need to switch to a fuel cell or something?

 

[96gt4.6]

@96gt4.6 I completely agree with you on many points. However, I think I would have tried lowering the "low" duty cycle before giving up on the dual pumps. Another option would be to change the inferred rail pressure vs flow, as this pressure is used to modify the injector flow rate it expects to get.

I'm working on something similar, but to run the GT500 bucket off of a pair of FPDMs in a gen3. I'd like to know more about your wiring setup. Also, I have the GT500 fuel line with filter ready to go, but not 100% certain it's the same size fitting at the firewall or if I'll need to drop the tank to swap the line out. I'd appreciate your feedback on this.

As for the DW400's abilities to run E85, I'm actually doing that now. I'm running a DW400 (with check valve) on a BAP at 18 volts. I've been able to support 680 lb/hr of fuel flow with pressure dropping to about 52 psi. This is good enough to support a Gen V whipple on the 3.25 pulley at .77 lambda in 80 deg weather, but it won't be enough in colder weather or if COT kicks in. I do understand the centrifs with stock fuel rails can't take the DW400 this far, though.

Thanks for the notes and feedback Mike, I enjoy visiting with a like minded individual!

So, on the wiring. Being as I work at a Ford dealer, when I bought the OEM GT350 pump, I also bought the pigtail that plugs into it (you have to, as the GT's pigtail/pump connector is different and missing 1 cavity you'll need for the GT350's dual pump setup). I wanted the car to look OEM, and since the GT350's fuel system requires two FPDM, and consequently two power feed circuits, I just added the 2nd fuel pump relay, and fuse, into the OEM underhood fuse box like the GT350's was. This way, you have a redundancy for power/fuel if you lose power on the GT's existing pump power circuit. I accomplished this by purchasing a fuse box from a wrecked GT, and using the pins from the box to pin my box, and run 1 wire discretely back to where the GT350's dual FPDM's mount. I also purchased the GT350's FPDM mounting bracket, so it all looks nice and neat and OEM.

You can pretty much do anything you want with commanded fuel flow in the tune, it won't matter. The GT's fuel system is always on 'low' output regardless of the settings in the tune. It's merely an on/off switch as far as when it goes to 'high' flow mode.

The only way around this I had found, would be to run the GT350's operating system (I did not check to see if this was possible on the GT's computer as some models utilize different physical ECU's), and you would at that point have to run the GT350's fuel rail pressure sensor as well, and wire it into the PCM connector. Then, the system would be true PWM based and only then would the pressure be regulated by the ECU via fuel pump speed.

The GT's fuel system is very simple. There is a mechanical regulator built into the bottom of the fuel filter assembly that bleeds off system pressure to 55 psi. When you go 'high' demand, the ECU commands the FPDM up to 14ish volts so the pump runs full speed to support the additional needed flow. You can actually do this with the stock GT pump as well by commanding high flow and you will notice fuel pressure does not change much at all, about 4 psi, and that's simply because it's outrunning the regulator's ability to bleed pressure due to high flow with low demand at the rail. The ecu actually does this test on it's own on every startup, you will see the fuel pressure run about 60psi for about 5 seconds after the end starts, then fall back, that's the self-test for the high/low demand happening.

Fuel line.

On S550 the GT's fuel line and the GT350's is identical as far as size (3/8"), and routing. The only difference is the GT350's line is sectioned for a fuel filter just under the drivers seat area. They did this because when they added the 2nd pump in the basket, there was no longer room for the fuel filter, so it had to be moved external.

Good to know on the BAP with the DW400! I'm only targeting about 750ish WHP on E50, and I think I can achieve that with a BAP and DW400. I also have the model with the check valve. It's been installed for about a year now, 0 problems, what a great drop in solution it has been!

The GT350 project pretty much got shelved. I still have the fuel line installed in the car, as you have to lower the tank and exhaust to remove it, so I just left it and fabricated a straight through piece of line where the fuel filter used to go, as when I went DW400 I had to re-use the GT's stock fuel hanger/bucket which already has a fuel filter, and I figured having two filters would cut down the total available flow rate. I do plan on removing the fuel line, at some point.

All in all, it was about a $1k waste of time at this point, between the GT350's pump/electrical pigtail/2nd FPDM/GT350 fuel line, all just to end up back at a DW400 drop in solution. I would have been better off doing the DW400/BAP in the beginning, and money ahead.

HOWEVER. If a guy were to drill/tap the GT350's pump hat, install a return line and regulator underhood like the article that did this fuel system swap did, it would indeed be a very cheap and reliable fuel system for the money and HP it could support as they proved in that article. But, what hung me up, is every bulkhead fitting I found for doing that swap, I just didn't trust, simply because past 1/2 tank of fuel these fuel pump locations are completely below fuel level. So, if that bulkhead fitting leaked at all, there is potential for emptying many gallons of fuel in your garage/ect. I just didn't like this idea.

There are several other options on the market for plug and play fuel systems, but it seems all do away with the fuel pump bucket, which then creates problems below 1/2 tank of fuel without the bucket scavenging system being operational. I just enjoy being able to get on the car without always having 1/2 tank or more of fuel, which is why I really want to stick as close as I can to an OEM fuel delivery setup which are designed for this by nature.

I haven't looked into anything GT500 yet, but I did start to nose into parts differences in the parts catalog, and I do remember the fuel tank being entirely different, due to internal siphon/pump design differences if I recall. At that point, given my HP goals in mind, I abandoned it all and went DW400.....

 

[engineermike]

Thanks for the feedback!

So when swapping the line you can just lower the exhaust some and tank? Driveshaft can stay in?

I was told that the gt350 bucket just has two gen2 pumps and the gt500 bucket has two gen3 pumps. The gt500 tees off the outlet of the non-Venturi pump and sends the flow to the passengers side pickup. My theory is that it’s there just to ensure the passengers side doesn’t suck air if that side goes low. I’m planning on calling it at the bucket though.

 

[96gt4.6]

Thanks for the feedback!

So when swapping the line you can just lower the exhaust some and tank? Driveshaft can stay in?

I was told that the gt350 bucket just has two gen2 pumps and the gt500 bucket has two gen3 pumps. The gt500 tees off the outlet of the non-Venturi pump and sends the flow to the passengers side pickup. My theory is that it’s there just to ensure the passengers side doesn’t suck air if that side goes low. I’m planning on calling it at the bucket though.

Ope, forgot about that! Yes, you'll need to remove the driveshaft as well since the tank straddles it.

Interesting on the GT500 pump setup. It's been about a year since I have put any thought or research into this, since the current setup has satisfied my needs presently. I have a lot of pictures and video of the failed attempt, but never have got around to getting them up here.....

 

[engineermike]

@96gt4.6 how did you handle the FPM signal/wiring?

 

[96gt4.6]

@96gt4.6 how did you handle the FPM signal/wiring?

I spliced the FPC wires together (this is how it's also done on GT350 as per the OEM wiring diagram), as this is just the ECU's request line. The FPM line I left alone on the OEM GT's FPCM, and the secondary pump FPCM I left the FPM wire open. This is merely a feed back line to the ECU so that faults with the fuel pump (windings open/shorted, current draw high/ect) can be communicated to the ECU so the MIL/Wrench light and corrective actions can be carried out such as power limiting/ect.

 

[bankyf]

I have purchased the parts and had planned on working with Mike to try out the GT500 fuel pump/line, but a lack of time has prevented that from happening. In the mean time, this caught my attention and I am somewhat holding off to see what they come up with. I reached out to them for an update on release date and pricing, but all he could tell me was "soon".

https://www.kpmmotorsport.com.au/kpm-news/12662/

Though it appears to be pricey, it seems to check all of my boxes.

 

[Grimreaper]

I reached out to them as well. I suspect there are some misunderstandings on fuel system variances across the coyote years/models and different markets that go unnoticed until tried. Same response.

Their system starts at a high pressure and decreases pressure as flow increases by design. Injectors will end up picking up the slack unless they are undersized and needed the delta a hi psi system would provide.

Think a few of us would pay for the ability to port the fueling control code like swapping legos.

The hard line is a restriction at the level you guys are pushing as well as the molded connector in the hat. Is the gt500 hardline same ID as yote/350? What about the molded connector?

 

[Midwestracer]

Bump

Sponsored