Issue link: https://read.dmtmag.com/i/47076
BIG RIG BASICS JOHN BAXTER 3 1 Filtration 2 maintenance T oday's injection systems use tight clearances and operate at ever increasing pressures. This means you need to replace your fuel filters at recommended inter- vals, or even before, to avoid a breakdown. Most truck fuel systems have a primary filter on the suction side of the fuel pump and a sec- ondary filter on the pressurized side between the pump and injec- tion system. The primary filter is designed to separate water and larger particles from the fuel, pro- tecting the fuel pump as well as the injectors. The secondary filter First, service the fuel/water sep- arator — in this case a Davco unit used by many engine manufac- turers. Service the unit at the mile- age recommended in the service manual, or whenever the fuel level rises to the line. 1 FUEL FILTER MAINTENANCE Job difficulty on a scale of 1-10: 6 out of 10 Tools and materials needed: 22 TRUCKERS NEWS DECEMBER 2011 Fuel filter service will help prevent roadside breakdowns and prolong the life of your injection system can catch fine particles because of the pressure generated by the fuel pump. Replacement filters must be of the right micron rating, or fineness. Use the OEM filter or one with the correct "cross number" in a parts book that lists filters by engine application. 4 5 2 3 4 5 Using the narrow portion of the special wrench, loosen the cap at the top of the unit by turn- ing it counterclockwise and then remove it by hand, placing it on a clean rag. With the engine off, place a drain pan below the fuel/water separator, and then open the drain cock and allow the fuel to drain completely. Close the cock snugly. Slide the wrench down over the filter until it fits around the large attaching nut at the bot- tom, and turn the nut counter- clockwise until loose. Then turn it off the threads and remove the nut and the large, plastic housing, put- ting them on a clean rag. Gently pull the filter cartridge up and off the seal at its base. Make sure the green seal stays on the filter.