What is the function of a flow divider (spider) in port fuel injection?

• A. To filter contaminants from fuel.
• B. To increase fuel pressure at the rail.
• C. To distribute fuel evenly from the rail to all injectors for uniform cylinder fueling.
• D. To connect the fuel return line.

Answer: (C)

Distributing fuel evenly from the rail to all injectors to ensure uniform cylinder fueling is the main job of the flow divider, or spider, in a port fuel injection system. It sits at the end of the fuel rail and splits the high‑pressure fuel into several separate, matched paths to each injector. Because each branch is designed to present similar resistance, the pressure drop is the same across all paths, so each injector delivers a similar amount of fuel. This balance helps maintain smooth idle, consistent power, and predictable emissions across all cylinders, and it also helps dampen pressure pulsations in the rail. It’s not a filter, so it doesn’t remove contaminants; it doesn’t increase rail pressure—that’s the job of the pump and regulator; and it doesn’t connect the return line—return routing serves a different purpose.