Fuel System - Cabby Info Fuel System. For fuel system troubleshooting & DIY guides and tips, please refer to the individual fuel system sections. Note: "CIS" has been replaced throughout this website with "K-Jetronic".K-Jetronic is the system's actual name (used everywhere outside North America), which is one type of continuous injection system. Volkswagen Golf, Cabriolet (1985-1993) - Fuel & Intake Fuel System for Volkswagen Golf, Cabriolet (1985-1993): Fuel Filters, Fuel Lines. Porsche / BMW / Mercedes / Audi; Volkswagen; Saab / Volvo When fuel filters get clogged, they can cause all sorts of problems, including clogged injectors, and contaminated fuel lines. Many times changing a fuel filter can make an old car run like new.