2012 GT500 switching to return style fuel, few questions

[Seer]

So I have decided to switch to a return style fuel system on my rebuild. I have been given conflicting information from various tuners and manufacturers of these fuel systems.

Scenario 1.

Install Return Style Fuel System like how the instructions say, which is to install new hat/return style pumps into the tank and disable the FPDM's in the tune and just ltrigger off the fpdm's with a relay and let the regulator on the line do its work. These seems to be the easiest scenario.

Scenario 2.

I am being told that my year 2012, lacks the ability to tune out some of the trouble codes of bypassing the FPDM and having a return style pump run 100% of the time (like how they are designed) whch could cause issues like crank relearns etc.

So it was recommended that I install a return line and regulator like a return style system, as well as a new hat with larger pumps but maintain the FPDM's and just upgrade their wiring, as in run a wire from the battery straight to both FPDM's then upgrade the wiring to the hat. This second scenario requires zero tuning adjustments. This seems like a "hack" or a "trick" to the returnless system.

Thoughts?

 

[chuck@evoperform]

PM sent

 

[908ssp]

I don't know anything about the first type not working in 2012s. That system works fine and is the simplest and can be tuned the most aggressively in earlier cars. The second system does have some advantages but might be tricky to tune correctly and get those advantages working for you. The biggest advantage I see in a return system is that with the pumps running on full all the time and the regulator near instantaneous response you can be more aggressive with your tune and throttle response. If you have to wait for the FPDM to ramp up the speed of the pumps to maintain pressure than you loose that advantage and might as well stay with the non-return system. So how do you get the pumps pumping at a higher than needed pressure but not flat out when the pressure relief valve is lowering the fuel pressure back to what you want to run. Seems to me that the pumps will run full on if there is a relief valve in the system in which case you shouldn't need the FPDM in the system at all. The trick setup would be to have the pumps pumping say 20% extra fuel which the relief valve then returns to the tank. This way the pumps aren't running flat out all the time. If the point of leaving the FPDM is simply to turn off warning lights you might want to ask a few tuners about that as it might be possible for a more experienced tuner to shut off the warning lights.

 

[Seer]

I don't know anything about the first type not working in 2012s. That system works fine and is the simplest and can be tuned the most aggressively in earlier cars. The second system does have some advantages but might be tricky to tune correctly and get those advantages working for you. The biggest advantage I see in a return system is that with the pumps running on full all the time and the regulator near instantaneous response you can be more aggressive with your tune and throttle response. If you have to wait for the FPDM to ramp up the speed of the pumps to maintain pressure than you loose that advantage and might as well stay with the non-return system. So how do you get the pumps pumping at a higher than needed pressure but not flat out when the pressure relief valve is lowering the fuel pressure back to what you want to run. Seems to me that the pumps will run full on if there is a relief valve in the system in which case you shouldn't need the FPDM in the system at all. The trick setup would be to have the pumps pumping say 20% extra fuel which the relief valve then returns to the tank. This way the pumps aren't running flat out all the time. If the point of leaving the FPDM is simply to turn off warning lights you might want to ask a few tuners about that as it might be possible for a more experienced tuner to shut off the warning lights.

I think there is more to it than shutting off warning lights.

since I am doing the fuel system in a new short block, the errors happening in the background even though a light isnt showing, may prevent me from doing a crank position relearn.