Silver02Z28

iTrader: (2)

I just got off the phone with Jim Bell, and I was asking about the KB Boost A Pump. He explained it to me, and I now understand how the BAP works, but now I'm really confused about how we can run non-pulse width modulated fuel pumps in our returnless fuel systems.

Many of us run aftermarket high flow fuel pumps on our stock returnless fuel systems. My understanding is that the PCM controls pulse width to the fuel pump and the fuel pump acts like a regulator, varying flow and pressure.

How can this work with a constant voltage aftermarket fuel pump? It seems to me that varying the voltage will burn out the constant voltage pump after a while.

Can the experts clear this up for me?

Nasty N8

iTrader: (33)

These are constant volt pumps they run a reg in the tank assembly. Shutting the power on and off would hurt the pumps but just rising it a few volts is just fine.

Nate

Silver02Z28

iTrader: (2)

I see. So the stock fuel pump is a constant voltage pump and is not pulse width modulated?

Gary Z

This is not correct. There is no fuel pressure sensor on our cars and therefore the PCM cannot regulate fuel pressure.

Gary Z

True.

Silver02Z28

iTrader: (2)

Thank you guys, that makes sense. What would be the benefit of a Boost A Pump other than ease of installation over a 255 l/hr in-tank pump? Would you just use the BAP if you are still dropping fuel pressure in a boosted or N20 application?

RedHardSupra

iTrader: (1)

remember that raising voltage isn't directly proportional to fuel pressure. then on top of it, you got injector flow that scales by the square root with the new to old fuel pressure ratio. so basicallly you can jack up your voltage like 50%, get maybe 30% extra pressure out of it, and that 30% will translate to 14% extra flow at the injector. so you're stressing the pump by working it way out of intended range, yet gain next to nothing. the numbers just work against you here, just get a bigger pump.