An outboard fuel line runs from the tank to the engine through a primer bulb, with a connector at each end. Engine-side connectors are largely brand-specific, so buy the fitting made for your engine’s make and the tank-side fitting for your tank. Use marine-rated fuel hose of the inside diameter your engine maker specifies, secure it with stainless clamps, and fit the primer bulb with its arrow pointing toward the engine.
Parts of an outboard fuel line
- Tank connector that fits the tank’s fuel pickup fitting.
- Fuel hose, rated for marine fuel use.
- Primer bulb with a one-way valve at each end; the arrow shows fuel flow toward the engine.
- Engine connector that snaps onto the engine’s fuel fitting.
Connector types
Quick-connect fittings differ between engine makers, and older and newer engines from the same maker sometimes differ too. Match the fitting to your engine’s make and era, and check that the O-ring inside is present and not cracked; a worn O-ring lets air into the line, which causes lean running and stalling.
Hose type and size
Use US Coast Guard rated marine fuel hose, which is printed with its type, such as A1 or B1, along its length. Low-permeation versions are marked with a 15 after the type. Automotive hose is not a substitute. Small and mid-size outboards commonly use 1/4 to 3/8 inch inside diameter hose; follow the engine maker’s specification, since a line that is too small can starve a larger engine at full throttle.
Signs your fuel line needs replacing
- Cracked, sticky, swollen or stiff hose.
- A primer bulb that will not firm up or collapses while running; see outboard primer bulb.
- Fuel smell or wet fittings.
- Air bubbles in a clear fuel filter bowl.
- Engine that dies at higher speed but restarts after you squeeze the bulb.
Ethanol fuel speeds up hose and bulb deterioration; see ethanol in boat fuel.
Installing a new line
- Cut the hose square to length with no tight bends or kinks.
- Fit the primer bulb with the arrow toward the engine, close enough to the engine that you can reach it.
- Push the hose fully over each barb and secure it with stainless clamps.
- Squeeze the bulb until firm, then check every joint for leaks before starting.
Built-in tanks
Boats with built-in tanks usually have an anti-siphon valve at the tank outlet. A sticking valve can starve the engine at higher speed; see outboard loses power at full throttle.
Related
See outboard fuel filters, outboard won’t start and outboard runs rough. Browse engines on outboard motors.
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