For Side-Injected Mercury EFI using injector style 24-98818
On Mercury Racing and high-performance side-injected EFI outboards, injector sealing is critical to consistent fueling. The Mercury Racing EFI Fuel Injector Upper Grommets and Seals 25-99123 and 26-94219 support the injector family commonly referenced as 24-98818, helping the injector seat correctly in the front half / side-injected block and maintain a stable, leak-free interface under vibration and heat.
What these grommets and seals do in the Mercury side-injected EFI system
These components create the sealing and support interface between the injector and the side-injected block. A proper seal helps prevent fuel leakage and reduces the chance of unwanted air paths that can lead to inconsistent fueling. They also help protect the injector pocket from moisture and debris and provide a cushion that reduces vibration and helps the injector stay seated through heat cycles and high-RPM use.
Why worn grommets can create performance problems
Over time, grommets and seals can harden, shrink, or tear. When they lose elasticity, the injector may not seat correctly, which can cause seepage, air leaks, or cylinder-to-cylinder fueling differences that get mistaken for injector or ECU issues. If you’re servicing injectors, rails, or doing a rebuild, replacing the grommets at the same time is inexpensive insurance
.
Common Mercury Racing / performance models that use this side-injected setup
These upper grommets and seals are commonly associated with Mercury’s legacy side-injected EFI platforms, including 2.0 Liter Champ (F1), 2.4L Bridgeport, 260 EFI, 280 ROS, 300 Drag, and S3000, along with race applications.
Installation notes that keep the seal right
Clean the injector pocket and sealing surfaces, then install carefully so the seal doesn’t pinch or tear. Light lubrication helps prevent rolling a seal during assembly. A damaged or mis-seated grommet can create fuel smell, seepage, or a lean-condition headache that only shows up under load.
Part numbers for reference
25-99123 and 26-94219 for side-injected EFI using injector family 24-98818.
Select:
Kit 1: Six (6) Outer Upper (Larger #22) Mercury Racing EFI Fuel Injector Upper Grommet 25-99123
Kit 2: Six (6) Inner Lower (Smaller #21) Mercury Racing EFI Fuel Injector Lower Seal 26-94219
Kit 3: Twelve (12) of the larger and smaller grommet seals from Kits 1 and Kits 2.
Contact Mike Hill at mike@buckshotracing77.com with any questions.