Fuel Quality

Fuel Quality Diagnosis

Fuel quality may cause driveability problems such as hesitation, lack of power, stall, no start, etc.

Certain driveability problems can be related to fuel quality. Fuel testing is limited. Therefore, all other system checks must be performed (e.g. Powertrain System, Fuel System, Ignition System, Emission System) before fuel quality is diagnosed. If these checks fail to solve the problem, gain information from the customer about when the condition occurs, when and where the fuel was purchased, and which octane level was used. Ask the customer to change fuel brands. If the symptom persists, perform the Fuel System Diagnosis Alcohol in Fuel test. If this is not conclusive, drain the tank and refill with a known good quality fuel.

Due to increasing awareness towards vehicle emissions (Evaporative and Exhaust) and their impact on the environment, federal regulations are limiting certain characteristics of fuel. These limitations are causing driveability problems that are extremely difficult to diagnose. In order to make a diagnosis, a basic understanding of fuel and its effects on the vehicles fuel system must be gained.