Mercury - Gen III Cool Fuel Module Cover & Seal MPI Series Stainless and Aluminum 8M0178981. Overview. Anyone who's spent time around a MerCruiser MPI engine knows how important the Cool Fuel system is. It's one of those components you rarely see, but you absolutely feel its influence every time you push the throttle forward. When the fuel stays cool and clean, the engine runs smoother, pulls harder, and just feels more willing. That's why keeping that system protected with the right parts matte