GT350 Dual Pump in 2015 Mustang GT

[Lads1719]

This is how we do them in house and they look 100% OEM when done.

I take it you‘ve done this a few times before, so obviously it works. What type of HP numbers are you typically supporting up to ?

I’m on a Roush blower making 650. I’m not convinced that I have to have a return system just to run e85 at that hp level, yet it’s all I hear.

thanks for the advice.

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[john@fatfab]

On a turbo cars we can get right around upper 900 whp on E85. Blower cars would probably be around mid 800 on E85.

 

[john@fatfab]

Btw you will need to add a fuel filter. The single pump has the filter built into the fuel pump assembly. On factory twin pump cars they are equipped with a fuel filter inline. The nice way to do it would be to get a hold of the factory feed tubes from and filter from a GT350. If you didn't want to mess with that you could make a fuel line from where the factory line comes up the fire wall and run it over to the drivers side fender well and mount your filter down below the abs stuff then run a line back up from there back into the fuel rail

 

[96gt4.6]

Btw you will need to add a fuel filter. The single pump has the filter built into the fuel pump assembly. On factory twin pump cars they are equipped with a fuel filter inline. The nice way to do it would be to get a hold of the factory feed tubes from and filter from a GT350. If you didn't want to mess with that you could make a fuel line from where the factory line comes up the fire wall and run it over to the drivers side fender well and mount your filter down below the abs stuff then run a line back up from there back into the fuel rail

Thank you sir! This answers everything I was looking for about doing this. I really appreciate you sharing the information!!

 

[96gt4.6]

Btw you will need to add a fuel filter. The single pump has the filter built into the fuel pump assembly. On factory twin pump cars they are equipped with a fuel filter inline. The nice way to do it would be to get a hold of the factory feed tubes from and filter from a GT350. If you didn't want to mess with that you could make a fuel line from where the factory line comes up the fire wall and run it over to the drivers side fender well and mount your filter down below the abs stuff then run a line back up from there back into the fuel rail

John, would you happen to know if the supplied rubber fuel rail cross over lines in the Whipple kits are E85 rated? Looks like the manufacturer information printed on them are Avon Greenbar, with an SAE rating of J30R12, but I'm having trouble finding much about this rating. Before I re-worked them and the fittings with PTFE lines, I wanted to see if perhaps they were up to the task, as it's pretty space limited under the blower, so why change them if they will work I thought.

Thank you sir! Getting ready to install this setup and see how she does.

 

[Jackson1320]

John, would you happen to know if the supplied rubber fuel rail cross over lines in the Whipple kits are E85 rated? Looks like the manufacturer information printed on them are Avon Greenbar, with an SAE rating of J30R12, but I'm having trouble finding much about this rating. Before I re-worked them and the fittings with PTFE lines, I wanted to see if perhaps they were up to the task, as it's pretty space limited under the blower, so why change them if they will work I thought.

Thank you sir! Getting ready to install this setup and see how she does.

Starting in the 80s/90s all fuel lines have been made e85 compatible. Every sense they started putting ethanol in gasoline

 

[96gt4.6]

Starting in the 80s/90s all fuel lines have been made e85 compatible. Every sense they started putting ethanol in gasoline

For sure, but what kind of bugs me is on OEM's that are E85 compatible, the fuel rails are even different.....good example would be Silverado 1500's 99-05ish, they had a unique rail (stainless) and the non E trucks were plastic rails (same engine).

My thoughts on the hose situation are, there is a difference between intermittent exposure and constant exposure, and at what levels. E10 is pretty much standard blend across the board so all vehicle since the mid/late 90's are compatible with that like you said. However, I really am concerned with this hose with full E85 exposure, and what I'm worried about is flaking/losing some of the hose liner into the injectors once I run E here shortly.

My initial plan was to simply replace the hoses with appropriate fittings/PTFE lined hose, however space constraints and having to re-work how the rails are tied and fed together has me looking into if the supplied hoses are in fact, capable of the task before I proceed.

 

[96gt4.6]

Just received word from Whipple that we're good to go on E85 with these, you da man Jackson, thanks again!

 

[Jackson1320]

Just received word from Whipple that we're good to go on E85 with these, you da man Jackson, thanks again!

So your good to go. Enjoy

 

[96gt4.6]

Well the pump certainly looks nice. Also have the GT350 fuel feed line and secondary FPDM to wire in with oem pigtails like Fathouse suggested.

Will get it all in soon and report back. I am doing pressure @ rail readings and voltage readings at each pump during tuning as well just to make sure everything supplies as it should be on full E85.

 

[96gt4.6]

I am now in the process of the installation.

Get a second FPDM. Don't mess with a hop switch. There is room in your factory fuse box to add another fuel pump relay next to the existing fuel pump relay and fuse. Splice the trigger wires from the existing FP relay to control your new added relay. Run the power from that relay to new FPDM. You can pick the ground from the ground point near the seat belt retractor(same spot as the existing FPDM gets it ground). Then splice the control and diag wire from the existing FPDM (these are the 2 small gauge wires) Then you just need to run the pump power and ground output from the FPDM to the power pins for the second pump. You can get a fuse box from car-part.com you can use to get the connectors out off to add the relay and fuse to your fuse box. If you source the FPDM connector and the GT350 FP connector with pins you can wire it exactly like a stock GT350 would come stock. Lastly you will need a roll of coraplast cloth tape to wrap the new harness in. This is how we do them in house and they look 100% OEM when done.

John, I'm currently in the middle of this install and had a quick question.

I see the GT350 has a fuel rail pressure sensor, and it made me curious as to if the control strategy was different on the 350's vs GT, as in are the 350's pumps still a low/high operation, or a true PWM variable speed like some of the older Ford's were? Looking at the literature I have available, it appears perhaps they are just low/high.....but wanted a 2nd opinion for my curiosity.

Talking about the FPM circuit for the 2nd driver module, does that cause any issues with the diagnostic side of things being fed back to the ECU if the pump secondary windings have a problem on either of the pumps? I see the GT350 has a dedicated FPM circuit to the PCM for the 2nd driver module, i'm assuming so that it can keep tabs on the 2nd pump individually.

Currently in the process of the install now. I see Oz Tuning has a variant of this setup available with 2 2018+ F150 fuel pumps in place of the OEM GT350 pumps, and they are supporting upwards of 1k HP on a returnless system, and their beta kits used the GT350's OEM pumps for up to 800 wheel HP on E85, so this is great news!

Will update as I progress. I have also added a fuel rail pressure sensor to keep tabs on the pressure as tuning progresses on this setup, just to be safe.

Thank you for your help!

 

[engineermike]

Talking about the FPM circuit for the 2nd driver module, does that cause any issues with the diagnostic side of things being fed back to the ECU if the pump secondary windings have a problem on either of the pumps? I see the GT350 has a dedicated FPM circuit to the PCM for the 2nd driver module, i'm assuming so that it can keep tabs on the 2nd pump individually.

There are 5 different errors that can be transmitted back through the FPM circuit. If you tie both FPM wires together and everything is fine, then it will work fine as long as the PWM phase is sync'd up. However, when two are tied together then only 2 of the 5 will work due to how the PWM signals interact. Secondary winding error will actually still work, but invalid fuel pump control data, fuel pump driver module internal error, and fuel pump disabled circuit won't.

 

[96gt4.6]

So, little update.

Either I had a defective GT350 pump assembly, or the GT350 uses PWM to control pump pressure, as with the GT350 pump installed, I had a fuel system pressure of nearly 100 psi. What appears to be a fuel pressure regulator on the 350's pump/hanger assembly, may simply be a safety relief valve by what I can tell.

The GT's pump has the regulator built into the end of the fuel filter assembly, and cuts the fuel pressure to 55 psi. Further review, the GT350 also uses a fuel rail pressure sensor, and the OEM manual appears to show GT350 is also PWM controlled pumps to regulate fuel pressure.

Knowing this, I do not see how this pump setup would work in a GT where there is no way to control pump speed, and therefore pressure.

 

[engineermike]

@96gt4.6 I believe the gen2 does use PWM pump control but it's not continuously variable or feedback control like 5.2 and Gen3. I think it can be made to work with the dual pump setup, assuming you still have the FPDM(s) and access to the tune.

The Gen2 appears to use a hi/low pump PWM control. The stock breakpoint appears to be 48 lb/hr, high duty cycle is 98% and low is 68.5%, all of which can be adjusted to keep the pressure in control.

 

[96gt4.6]

@96gt4.6 I believe the gen2 does use PWM pump control but it's not continuously variable or feedback control like 5.2 and Gen3. I think it can be made to work with the dual pump setup, assuming you still have the FPDM(s) and access to the tune.

The Gen2 appears to use a hi/low pump PWM control. The stock breakpoint appears to be 48 lb/hr, high duty cycle is 98% and low is 68.5%, all of which can be adjusted to keep the pressure in control.

Mike, that is correct on some parts.

The S550 has two fuel control methods from what I can see based on the OEM manuals. The Base/GT models use a FPDM, which has a low/high switch point with a configurable break point in the tune like you have seen. The FPDM in these cars essentially works as an on/off relay with a slightly reduced voltage output to the pump in low fuel demand mode. Fuel pressure on these models is regulated by the fuel pressure regular, built into the bottom of the non-serviceable fuel filter of the pump hanger assembly.

The GT350 models are different. They utilize a fuel rail pressure sensor, and use the FPDM to control pump speed based on desired fuel demand. The GT350 pump hanger has dual pumps, and no filter integrated into the hanger/pump basket assembly, it's located in the fuel line under the driver's seat externally. The GT350 has a pump-relief poppet in the hanger assembly, located in the pump outlet line shortly after the Y connection. This relief valve is slightly below the pump's maximum rated output pressure of ~95 psi. Fuel pressure is regulated through PWM of the pump's supply voltage, and feedback to the ECU on rail pressure is provided by the fuel rail pressure sensor, which allows the ECU to demand more or less PWM of the pumps to keep rail pressure at desired.

So, during my retrofit of the GT350's fuel system into my GT, I installed a GT350 pump/hanger assembly, and added in the secondary relay/fuse and wiring in the OEM fuse box under the hood like the GT350's is. Then, installed the 2nd FPDM and wired into the OEM GT350 pump assembly. I also installed the GT350 specific fuel line with the external filter. This now makes it a GT350 fuel system in both terms of hardware and electrically.

Initial startup was ok, but the fuel trims were wayyyyyy rich, with the ECU pulling 25% whereas this car was 2-3% prior. I immediately installed a manual fuel pressure gauge, and found the rail pressure at 90ish psi, whereas on the OEM GT pump it was a steady 55-60psi, which is the rated pressure. Ok, so what's up with this. I then began to dive into the OEM service literature and found where Ford claims the GT350 is PWM controlled pumps in concert with the fuel rail pressure sensor to maintain desired pressure, and the rail pressure specificaton for GT350 was shown as variable.

Knowing this, I then went into my tune and moved the hi/low breakpoint (even though high isn't used at idle) just to rule out the ECU commanding high for some reason (it wasn't). The next step, I removed the GT350 pump assembly, and disassembed the releif valve located in the pump basket, and to my surprise it was adjustable. I moved the set screw back all the way, and had to cut 2 coils out of the spring to get the fuel pressure down by opening the relief valve like the OEM GT regulator does. This worked....but looking at the design of the valve, it's not designed to be a relief with fuel flow going by it at all times, and I had worries about it failing at some point being utilized in this manner.

At this point I scrapped the idea, and went to a DW400 drop in replacement for the GT's OEM hanger/pump assembly for the time being as it suits my needs in the interim. But, I still want to run full E85, so I will need to either move to an external regulator/return system to utilize this pump setup, or add a booster into the existing DW400 for the power levels I'm after.

This has been my findings on trying to utilize this setup on a GT with no return line installed like the article linked (I refuse to add a return line into the OEM plastic fuel pump hat due to safety concerns with the fuel level on these saddle tank systems going above the fuel pump when over 1/2 full, which can result in a leak/fire danger).

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