Diesel Fuel Injector O-Ring by Motorcraft®. 7 O-Rings Per Kit. Bring your vehicle’s fuel system back to its top shape with this top-notch part. Designed as a direct-fit replacement of your worn-out or malfunctioning part, it will provide easy, no-hassle installation and help restore proper fuel system functionality needed to keep your vehicle performing reliably, efficiently, and safely for many miles to come. This component is made to OEM standards so you can expect years of reliable function and hassle-free service.