Sierra Primer Bulb Assembly 5/16 Inch ID, 18-8004EP-1, Replaces Mercury 89396A38, 89396Q38, Johnson/Evinrude 174511

The Sierra Primer Bulb Assembly 18-8004EP-1 is a 5/16 inch ID fuel line primer bulb used to manually prime the fuel system on outboard and other marine engines before starting. Squeezing the bulb draws fuel from the tank through the line and into the carburetor or fuel injection system, helping the engine start quickly and run smoothly, especially after the boat has been sitting or the fuel line has been disconnected. The bulb is built from Floroelastomer (FKM) material, which gives it the traditional feel and operation boaters expect while standing up to continued exposure to modern fuels. It measures 7 1/2 inches overall length including the barbed connector ends, which are sized for 5/16 inch fuel hose and help create a secure, leak-resistant connection at each end of the primer bulb. The assembly is both EPA and CARB certified, meaning it meets emissions-related evaporative standards required for fuel system components sold for use on recreational marine engines. It is manufactured by Sierra International (Teleflex Marine) and functions as a direct equivalent to several original equipment primer bulbs, making it a straightforward replacement when an existing primer bulb has cracked, hardened, or lost its ability to hold prime. This primer bulb is sold and shipped as a single 5/16 inch ID unit.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-8004EP-1
• Manufacturer: Teleflex Marine
• Hose Size: 5/16 inch ID
• Overall Length: 7 1/2 inches, including barbs
• Material: Floroelastomer (FKM)
• Certification: EPA/CARB certified
• Weight: 0.29 pounds
• UPC: 808282289591
• GTIN: 00808282289591
• Warranty: Limited warranty

Replaces (OEM)

• Mercury 89396A38
• Mercury 89396Q38
• Johnson/Evinrude 174511

Frequently Asked Questions

What size fuel hose does the Sierra 18-8004EP-1 primer bulb fit? It is sized for 5/16 inch ID fuel hose, with barbed ends on each side of the bulb to secure the hose connection.

Does this primer bulb replace a Mercury primer bulb? Yes, the Sierra 18-8004EP-1 is a direct equivalent to Mercury primer bulbs 89396A38 and 89396Q38.

Is this bulb compatible with Johnson or Evinrude outboards? The 18-8004EP-1 also serves as a replacement for Johnson/Evinrude primer bulb 174511.

How long is the primer bulb overall? The Sierra 18-8004EP-1 measures 7 1/2 inches in overall length, including the barbed connector ends.

What material is the primer bulb made from? It is made from Floroelastomer (FKM), which gives it a traditional feel and operation while resisting degradation from modern fuels.

Is the Sierra 18-8004EP-1 emissions certified? Yes, this primer bulb is both EPA and CARB certified for use as a fuel system component.

How much does this primer bulb weigh? The Sierra 18-8004EP-1 primer bulb assembly weighs 0.29 pounds.

How do I install a primer bulb like the 18-8004EP-1? It installs inline on the fuel hose between the tank and the engine, with the barbed ends pushed into each length of 5/16 inch hose and secured with clamps; the arrow marking on the bulb should point toward the engine.

Is this a genuine Sierra part or an aftermarket copy? The 18-8004EP-1 is manufactured by Sierra International (Teleflex Marine), sold under the Sierra brand rather than as a generic aftermarket part.

What is included when I order the 18-8004EP-1? You receive one complete Sierra 5/16 inch ID primer bulb assembly, part number 18-8004EP-1.

Why would I need to replace my boat's primer bulb? Primer bulbs like the 18-8004EP-1 are typically replaced when the original bulb has cracked, hardened, or can no longer hold prime, which prevents the fuel system from priming properly before starting.