Fuel Systems

Oct 15, 2010

Fuel Systems Summary

  • Improved fuel delivery is a critical component to a successful engine performance upgrade.
  • A fuel system upgrade is one of the easier and more popular modifications.
  • A fuel system will not make power; the system supports power. An inadequate fuel system robs horsepower and can lead to engine failure.
  • High-tech, high-horsepower engines require high-tech fuel systems for proper fuel flow.
  • Speed and performance shops can profit from the demand for fuel delivery products, support equipment, fittings, fuel lines, filters, gauges and other parts necessary to finish the job completely.

Fuel System Components: Follow the Fuel

  • Fuel enters the tank or fuel cell through the filler neck, either a vented or non-vented device.
  • Flow starts at the tank (storage device).
  • Pump.
  • Fuel supply line.
  • Induction assembly

Fuel has two options for getting to the induction assembly.

  • Moved by a mechanical fuel pump;
  • Moved by an electrical fuel pump.

Basic Fuel System Physics

  • Pumping systems are vulnerable to pump suction problems.
  • High performance fuel systems run with the fuel pump located close to the fuel supply because the closer the pump can be to the fuel itself, the better the pump is going to work.
  • Any line or hose that leads from the tank or fuel cell to an externally mounted pump is going to have some degree of flow resistance and the longer the line or hose, the greater the resistance.
  • Eliminates an old problem for carbureted engines: vapor lock.

A high-performance engine needs enough fuel delivery to support the power requirements; over-sizing the fuel pump to some degree is best.

  • Fuel Filters
  • Often an overlooked part of the system; filter protects the pump from contamination
  • Filter must be fine enough to catch debris downstream; not so fine as to cause a flow restriction.
  • Always use a primary and a secondary filter.
  • Primary (40 to 100 microns): keeps large contaminants from entering the inlet side of the fuel pump.
  • Secondary (5 to 20 microns): keeps small contaminants from entering carburetor or fuel injectors.

Fuel Regulator

  • Brain of the system
  • Controls fuel pressure but does not restrict flow;
  • Regulator compensates for needle and seat opening on carburetors; injector openings on EFI systems.

Fuel Lines

  • Most vehicles are equipped with 3/8″ line, which is adequate to support naturally aspirated engines up to 600hp.
  • Nitrous or boosted applications and naturally aspirated engines making over 600hp will require a 1/2″ fuel line.
  • Fewer 90-degree turns will improve fuel flow.