Sierra Primer Bulb for Outboards 3/8" – Large-Volume Viton Valves, Stainless Springs

The SIERRA INTERNATIONAL 18-8005EP-1 is a large-capacity 3/8" primer bulb engineered to restore fuel flow quickly and reliably for outboards and small engines.

Designed and molded in-house by Sierra, this primer bulb replaces part 174512 and features double check valves with durable Viton balls and stainless-steel springs. Its 3/8" hose connection fits common marine fuel lines, and the generous bulb volume speeds the priming process so engines draw fuel with fewer pulls. Built for longevity and consistent performance, the 18-8005EP-1 focuses on material quality and functional reliability rather than cosmetic frills.

How does this primer bulb improve starting performance?

The larger internal capacity moves more fuel each stroke, reducing the number of pumps needed to get a steady flow. The double check valve arrangement prevents backflow and keeps fuel in the line between starts, which helps maintain a ready-to-start system.

• Large-volume bulb for faster fuel displacement
• Double check valves minimize backflow for consistent priming
• Viton valve balls resist fuel and ethanol breakdown
• Stainless steel springs maintain valve tension and durability

Will it fit my boat’s fuel line and replace part 174512?

This model is made for 3/8" hose connections and is specified as a direct replacement for part number 174512. Confirm your fuel hose inner diameter is 3/8" and check routing clearances to ensure the bulb will install without strain or sharp bends.

• Specifically sized for 3/8" inner-diameter fuel hoses
• Direct replacement for OEM 174512 designs
• Flexible body accommodates typical marine hose routing
• Molded construction reduces risk of seam leaks

What materials and design features extend its service life?

Sierra molds these bulbs in-house to control material quality and dimensional accuracy. The use of Viton valve balls provides superior resistance to modern fuels and ethanol blends, while stainless steel springs prevent corrosion-related loss of tension.

• In-house molded body for consistent wall thickness and fit
• Viton balls resist chemical degradation from fuel blends
• Stainless-steel springs avoid rust and maintain spring force
• Double check valves protect against siphoning and leaks

How do I install and maintain the primer bulb?

Installation is straightforward: cut the fuel line cleanly, push the hose onto the barbed fittings, and secure with appropriate clamps. Periodic inspection for softening, cracking, or fuel smell helps catch wear early; replace the bulb if you detect swelling, hardening, or visible damage.

• Install on 3/8" hose using clamps over barbs for a secure seal
• Position bulb away from heat sources and sharp bends
• Inspect regularly for cracks, hardening, or leaks
• Replace if performance drops or physical damage appears

Who is this for: The SIERRA 18-8005EP-1 primer bulb is aimed at boat owners, marine mechanics, and small-engine technicians who need a dependable, ready-to-install replacement for part 174512. It’s a good choice when you want a larger-capacity bulb that reduces pumping effort, uses fuel-resistant components like Viton and stainless steel, and fits standard 3/8" fuel lines. Choose this bulb when you prioritize reliable priming, long-term chemical resistance, and straightforward installation for outboard motors and portable engines.