Let my fuel flow!

Modern fuel injected engines, whether street or race, are marvelous things. Thanks to computers and fuel injection you can buy a Mopar SRT car that makes nearly 500 horsepower and gets over 20 mpg. And the systems are reliable, so reliable that most people never think about them. But fuel injectors live in a tough environment; they’re subjected to extremely high temperatures, potentially corrosive chemicals flow through them while their electric solenoids slam mechanical needle valves open and shut. Over time, issues arise that can be addressed with proper maintenance.

The ratio of air to fuel entering your engine for every power cycle is critical. Too much fuel creates an excessively rich mixture that can lead to deposits building up on the pistons, combustion chamber and valves and can decrease your fuel mileage. Too little fuel creates a lean mixture that in the worst case scenario can lead to engine damaging detonation. With a carbureted car, if the main jets are sized incorrectly or have varnish build up, the change in the air-fuel (A/F) ratio impacts all of the engine’s cylinders more or less equally. But with fuel injection, each cylinder has its own injector, so an issue with an injector can impact only a single cylinder.

We were invited to Larson Marine and Automotive, co-located with Bones Fab auto fabrication in Camarillo, California, to learn just how important fuel injection maintenance can be. Lyle Larson has been around engines and involved in drag racing since before Americans had ever heard of a far away place called Vietnam. He’s worked as a consultant to many of the biggest aftermarket names in the performance industry and researched the importance of proper fuel system functioning. Jim Bassett walked us through the process of inspecting, flowing and maintaining fuel injectors.

Left: This modified machine is used to test, flow, and clean fuel injectors. The usual process is to pressure test the injectors to make sure none leak, then flow them to test their spray patterns and flow rate, clean then reflow them. There are some proprietary things that Lyle and Jim do as part of their process that we aren’t free to disclose, but you’ll get a good idea of what they do here.