"Some models have experienced internal fuel rail deterioration. I've seen metallic flakes from these rails collect on the inlet screens of some Taurus V6s and Neons. In most instances, these were cars that were frequently and habitually driven with the fuel tank very low, and I hypothesize that excessive moisture condensation in the fuel tank may have been a factor. In the case of one of the Neons, I was faced with a floating misfire as the flakes shifted within the rail. Most of them eventually collected on the No. 3 and No. 4 inlet screens."
"Good fuel is usually readily transparent, although normally dyed to allow after-sale (or after-spill!) identification. Cloudiness or turbidity often accompany excessive alcohol and water content, but may also arise from very fine particulates in suspension. Friends who work as rental fleet technicians report encountering an increasing incidence of apparently intentional fuel watering whenever pump prices climb."
