Fuel pumps

[justjuiceit]

Can the stock pump handle 63 psi through stock injectors without the pressure dropping off at high rpms on an S13? My other question is what would be the advantage of the 190lph to the 255 lph inline fuel pump model? At 63 psi fuel pressure with stock injectors will the 255 provide more fuel? Thanks for any input.

[Redline240]

I have a similar question...i have a 255lph inline pump, will it be effective if i keep the stock intank? Do i remove the stock one and just use the inline? Where do i hook it up?

Redline

[huguetpj]

The press is regulated by the fuel pressure regulator. Pressure drops because of two things:

1. Big injectors -> high flow -> fuel pump can't flow as much2. High fuel rail pressure -> lower fuel pump flow -> fuel pump can't flow as much

Fuel pump flow is determined by both the fuel pump rating (255lph for example) and the fuel rail pressure. The higher the pressure the less fuel the pump can flow.

So, regarding justjuiceit questions:

1. Dunno about the stock pump at 63PSI2. More fuel at higher PSI3. Nope, since the amount of fuel entering the cylinders is determined mainly by 3 things: pulse width, injector CCs and fuel rail pressure. So if u keep the pressure at 63PSI, it doesn't matter what pump you have.

And redline, I belive that if you have an inline pump u don't take out the stock pump. But I'm not positive

[240marcuSX]

so, hugue, i can go ahead and switch out my stock pump with the 255 lph i have, and there wont be any affect??

[huguetpj]

The only effect I can see is if your pressure reg can't take the added flow from the pump that the fuel pressure might go up. I haven't installed my 255 lph HP pump yet, but I'll let you know in the next couple of weeks.

[C-Kwik]

The stock can provide a lot of pressure. But when you ask it to provide a lot of pressure and flow, it will run into problems.

A higher flow pump will do absolutely nothing over a working stock pump unless the flow and/or pressure capacity of the stock pump is exceeded.

And I'm only restating Huguetpj's responses in a different way to hopefully clarify and to back up his point.

[Redline240]

A higher flow pump will do absolutely nothing over a working stock pump unless the flow and/or pressure capacity of the stock pump is exceeded.

So if i install my 255 inline and keep my stock intank one in the inline will pick up the slack once the stock one maxes out?

Redline

[C-Kwik]

It would depend on a lot of factors. I don't have anout technical data on the stock pump or this inline pump. But for the most part, I think if the inline is rated higher, than the stock would only have to provide enough fuel to meet the flow demands, without having to meet the pressure demands. But you will need to confirm the stock pump can supply enough flow even at low pressures to keep enough fuel going to the inline pump.