Plastic or Metal Fuel Filters - MonteCarloSS Message Board Jun 04, 2008dont use the plastic after the fuel pump, they will blow up. One time i had one it was pumping like a heart to the puls of the fuel pump, it was expanding and contacting like almost a quarter inch!! i changed it out for a metal one right away. alot of people told me they would explode, i didnt belive them, but after seeing it pulse like that ill never use one after a fuel pump again, unless Are plastic fuel filters really that bad? [Archive Jan 05, 2015[Archive] Are plastic fuel filters really that bad? Duramax Hard Parts I installed a Napa Gold fuel filter with the plastic body on my LML about 2 months ago, it's one that I had bought probably a year ago and never used. PUROLATOR switched over to the metal filters from RACOR now. Friend of mine told me about it about 6 months ago.