When troubleshooting a late model engine exhibiting symptoms of lean operation, what should be checked first?

In diagnosing a late model engine demonstrating signs of lean operation, the first step is to check the fuel pressure in the circuit supplying the injectors. A lean condition typically means that the air-fuel mixture has too much air for the amount of fuel available; thus, ensuring that the fuel system is functioning properly is paramount. Low fuel pressure can indicate issues such as a failing fuel pump, clogged fuel filter, or problems with fuel lines, any of which could restrict the fuel flow to the injectors and lead to a lean mixture.

Maintaining adequate fuel pressure is critical because fuel injectors rely on a steady and sufficient supply of fuel to atomize and deliver the correct amount into the combustion chamber. If fuel pressure is too low, the injectors cannot function effectively, resulting in insufficient fuel delivery which directly contributes to a lean operating condition.

While checking fuel quality, air intake, or throttle position sensor voltage can also be important in diagnosing engine performance issues, ensuring that the fuel system has the correct pressure is a fundamental step in addressing symptoms of lean operation. Such an approach prioritizes the most common causes of lean conditions and helps pinpoint the problem efficiently.