The Science of a Fuel Pump..

[Phoenyx]

All:

I don't quite understand how an upgraded fuel pump gives more fuel to the injectors.

Suppose we have a typical bone-stock DSM. We throw on a Walboro 255lbs/hr fuel pump. Does that car automatically become rich? If so, how? It is to my understanding that the FPR will only allow so much fuel to the fuel rail, so that your only need for a fuel pump would be to have it deliver the fuel when the engine demands more. If this is so, if your stock fuel pump isn't maxed out yet, then what is the need for a larger one?

-M

 

[Defiant]

The ECU can demand more than a stock pump can deliver. However, a 255lph will overwhelm a stock FPR.

 

[autronicDSM]

By flowing more fuel in the same amount of time compared to stock. Actually fuel pressure regulator on DSM doesn't control flow to the fuel rail. It controls flow back to tank. Less going back creates more pressure. Since fuel can't flow back it has to flow through injector so higher pressure gives more fuel for the same pulse width.

Now as for walbro and stock regulator. Since regulator can't be adjusted and pump now flows lot more but return line can't flow more that fuel has no choice but to be injected and causing your car to run rich.