FI fuel upgrade options

phunk

You are right that the return system is the strongest solution to pressure drop. Tuning around a pressure drop can be reasonable if the pressure drop is extremely mild and consistent, but these are rare qualities of pressure drop. Once a piece of the system has reached the edge of its capacity, it will generally be pretty inconsistent as many day-to-day variables can shift the limits up and down.

A stronger fuel pump can sometimes alleviate the issue, but the nature of a returnless system really taxes the fuel pump output. No matter how hard your fuel pump works, the best it can do is hold 52psi inside the fuel pump module. When the flow restrictions through the fuel system begin to show as fuel is in high demand, the fuel pump's hands are tied, as it is allowed to output no more than 52 psi and anything extra will simply bleed out the regulator that resides right next to it. The pressure drop through the system will continue to grow as fuel demands grow.

A return system allows the pump to work harder for you by placing the regulator after most of the flow restrictions in the system, and blocking off the factory regulator port in the fuel pump module. Now the fuel pump is no longer regulated directly at it's output, and it will operate at a higher immediate pressure allowing it to push "harder" through the fuel system.

You can set the regulator to the factory fuel pressure setting and it will run the same pressure profile until where fuel pressure used to fall off, it will no longer fall (until much higher fuel demands).

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