Scepter Marine Primer Bulb 07494 | 5/16 in. Hose Barb

Scepter Marine Primer Bulb — 07494

The Scepter 07494 is a 5/16-inch marine fuel primer bulb built for outboard fuel-line assemblies. Its high-flow internal design features dual check valves that draw fuel toward the engine and prevent backflow when the line is at rest. Construction is gasoline- and solvent-resistant and rated for use with ethanol-blended fuels, including E10 and E15 marine fuel blends.

Specifications

• Part Number: 07494 (catalog format: 770-07494)
• UPC: 063923074947
• Hose Barb Size: 5/16 in. (fits 5/16 in. ID fuel hose)
• Internal Design: Dual check valves, high-flow priming
• Fuel Compatibility: Gasoline, ethanol-blended fuels
• Construction: Gasoline- and solvent-resistant materials

Compatible Applications

• Portable outboard fuel-tank systems using 5/16 in. ID fuel hose
• Replacement outboard fuel-line assemblies
• Custom marine fuel-line builds requiring a 5/16 in. primer bulb
• Repair of existing primer circuits where the bulb is hard, cracked, or no longer holds prime

Fitment — Verify Before Ordering

• Confirm fuel hose inside diameter is 5/16 in. — Scepter offers visually similar bulbs in 3/8 in. and 1/4 in. sizes
• Confirm existing fittings and connectors are compatible with your engine and tank
• Verify the fuel-line material is rated for the fuel type in use
• Confirm the complete system meets applicable marine fuel-system requirements

When to Replace

• Bulb has become hard, cracked, or permanently collapsed
• Bulb squeezes but will not firm up during priming
• Fuel drains back toward the tank between uses
• External fuel leakage is visible at the bulb or hose connections
• Internal check valves no longer hold prime
• Hose-barb connections are damaged or weeping

Installation Notes

• Confirm hose ID is 5/16 in. before installation
• Install with the fuel-flow arrow pointing toward the engine
• Push the fuel hose fully onto each barb before clamping
• Secure hose ends with suitable marine fuel-line clamps
• Route the bulb away from exhaust heat and abrasion points
• Prime the system and inspect all connections for leaks before starting the engine

Related Products

• Scepter Primer Bulb 5/16" Hose Barb — SCE-07494
• Scepter 05869 3/8" Primer Bulb
• Scepter Yamaha Female Fuel Connector – 5/16" SCE-05813
• Scepter Mercury Tank Bayonet Fuel Fitting – Metal (07497)

Parts Desk Insights

Best Use Case: Straightforward drop-in replacement for any outboard portable tank setup running 5/16 in. fuel line where the existing primer bulb has gone hard, collapsed, or stopped holding prime. The dual check-valve design primes quickly and resists fuel draining back to the tank — a common complaint with single-valve or low-quality aftermarket bulbs.

Common Issue: The most frequent ordering mistake is selecting a primer bulb by appearance rather than hose diameter. Scepter's 1/4 in., 5/16 in., and 3/8 in. bulbs look nearly identical on the shelf. Measure the inside diameter of your existing fuel hose before ordering. If your current bulb fits but drains back between uses, the check valves are likely failed — this is a normal wear item and does not indicate a fuel-system problem beyond the bulb itself.