Sierra Marine Fuel Primer Bulbs: Match Your Hose Size

Replacing an outboard fuel-line primer bulb starts with the fuel hose's inside diameter. Sierra Marine makes separate EPA/CARB-listed primer bulbs for ¼-inch, 5/16-inch and ⅜-inch fuel hose. The similar-looking black bulbs should be chosen by exact part number and the existing line size, not appearance alone.

Check three things before replacing a primer bulb

Fuel hose inside diameter

Read the size printed on the fuel hose where possible. A 5/16-inch hose is not the same as ¼ inch or ⅜ inch. Compare the correct barb connection before ordering.

Fuel-flow direction

Primer bulbs contain one-way check valves. Follow the marked fuel-flow direction and the fuel-system manufacturer's installation instructions when replacing a bulb.

Fuel-system condition

Inspect the hose, clamps and connectors for cracking, stiffness or leakage. A new bulb alone does not repair damaged hoses or a leaking connection.

Important: These listings are for individual primer bulbs with clamps, not complete fuel-line assemblies. The correct hose, tank and engine connectors must be identified separately, and all components must be suitable for the intended marine fuel system.

Sierra primer bulb MPN and hose-size comparison

The bulb body is listed as 7½ inches long for each product, but the intended hose barb size changes with the part number. Each listed bulb uses fluoroelastomer construction and check-valve components with Viton balls and stainless-steel springs.

Sierra part number Fuel hose inside diameter Bulb length Fuel hose included?
18-8002EP-1 1/4 in 7½ in No
18-8004EP-1 5/16 in 7½ in No
18-8005EP-1 3/8 in 7½ in No

How the three versions differ

18-8002EP-1: Fits the specified ¼-inch-inside-diameter hose arrangement. Verify your original hose and barb before installation.

18-8004EP-1: Intended for 5/16-inch fuel hose, a different connection size from the ¼-inch version.

18-8005EP-1: Intended for ⅜-inch fuel hose. It should not be forced into a smaller-diameter hose as a substitute for the correct connector.

These bulbs are described as EPA- and CARB-certified for their intended fuel-system applications. Match the actual fuel system and the required hose/connector standards rather than treating certification alone as proof of engine-specific compatibility.

Find the exact Sierra Marine primer bulb

Installation and safety checks

Work in a ventilated location away from sparks, flames and ignition sources. Follow the engine and fuel-system manufacturer's procedure to safely disconnect, replace and prime the line. Use approved marine fuel hose and compatible clamps, then check for leakage before operating the engine. Never operate a fuel system with a visible leak.

To identify a complete hose assembly or an engine-specific connector, compare our Sierra outboard fuel hoses by connector and diameter and Sierra marine fuel connector identification guide.

Common questions

Can I use a ⅜-inch bulb with a 5/16-inch fuel hose?

No universal compatibility is established. Use the manufacturer-specified bulb with the correct hose size and clamps instead of forcing a mismatched connection.

Does a Sierra primer bulb come with a fuel hose?

These three product listings specify the primer bulb with clamps, without a separate fuel hose. Complete hose assemblies are different products.

Are these bulbs compatible with every outboard motor?

They are identified by fuel-hose diameter, not a universal outboard motor fitment list. Confirm the hose and the engine's fuel-system requirements.

Can I arrange viewing or pickup?

UsedRVParts offers viewing and local pickup in Kelowna by appointment. Confirm the part and arrange a visit before travelling.

Quick part links: 18-8002EP-1 · 18-8004EP-1 · 18-8005EP-1

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