When it comes to keeping your Honda 400EX running smoothly, the fuel pump plays a critical role. This ATV, produced from 1999 to 2009, requires a pump that delivers between 2-6 PSI of pressure to meet its 397cc engine’s demands. While the OEM part (16700-HN1-A01) is a reliable choice, many riders explore aftermarket options for better performance or cost savings. For instance, the Fuel Pump from Kemso Racing has gained popularity for its compatibility with the 400EX, offering a flow rate of 1.5 gallons per minute – nearly 15% more efficient than some budget alternatives.
One common question riders ask is, “Can I use a generic fuel pump instead of a model-specific one?” The answer lies in specifications. The Honda 400EX fuel system operates at lower pressure compared to modern fuel-injected engines (typically under 6 PSI). Using a high-pressure pump designed for newer models could overwhelm the carburetor, leading to poor performance or flooding. Kemso Racing’s solution includes an adjustable regulator, allowing users to fine-tune pressure between 2-6 PSI using simple tools. This adaptability explains why 78% of surveyed ATV repair shops recommend pump kits with adjustable settings for 400EX rebuilds.
Durability is another key factor. Factory pumps last about 5 years or 1,000 hours of moderate use, but aftermarket versions vary widely. A 2022 study by ATV Insider compared 12 fuel pumps across 500 hours of testing. Units with reinforced polymer housings (like those in Kemso’s design) showed 40% less wear than all-metal counterparts in dusty conditions. One trail rider reported completing the 300-mile Nevada Rally without fuel issues after upgrading to a pump with dual filtration stages, emphasizing how proper filtration extends pump lifespan beyond the 200-hour mark common with basic models.
Cost considerations often drive purchasing decisions. OEM pumps range from $120-$150, while quality aftermarket options typically cost $60-$90. However, smart shoppers look beyond initial price tags. A pump requiring replacement every 2 seasons ultimately costs more than a $85 unit lasting 5 years. Mechanics note that 400EX owners who invest in pumps with integrated strainers save an average of $28 annually on filter replacements. Kemso’s kit includes a stainless steel pre-filter, addressing this exact pain point for budget-conscious riders.
Installation tips matter too. The 400EX fuel pump mounts vertically in a 2.75” x 1.5” space near the carburetor. Many riders overlook the importance of proper orientation – inverted installation can reduce pump efficiency by up to 30%. A viral YouTube tutorial by ATV Pro demonstrated correct installation in under 20 minutes using basic hand tools, resulting in a 22% horsepower improvement on dyno tests compared to poorly installed units. Whether you’re rebuilding a barn-stored 2002 model or maintaining a daily rider, matching pump specifications to your usage patterns ensures optimal performance.
Maintenance routines significantly impact fuel system health. Riders who clean their pump filters every 50 operating hours report 60% fewer engine stalls than those following factory 100-hour intervals. For example, Missouri off-road enthusiast Sarah Jenkins doubled her 400EX’s pump lifespan by adding an inline fuel water separator – a $15 modification that prevented ethanol-blend fuel corrosion. As ethanol content in gasoline continues rising (now up to 10% in most states), corrosion-resistant components have become essential rather than optional upgrades.
When replacement becomes necessary, cross-referencing part numbers prevents compatibility issues. The Honda 400EX shares some fuel system components with the TRX400X sport quad, but pump specifications differ slightly. A 2023 mix-up at a Florida dealership saw 17 customers receiving TRX400X pumps that failed within 80 hours on 400EX machines. Always verify flow rates (1.2-1.8 GPM ideal) and connection types (5/16” fuel lines standard). Kemso Racing’s direct-fit kit eliminates this guesswork, with users reporting 98% “plug-and-play” satisfaction in recent forums.
Ultimately, choosing the right fuel pump blends technical specs with real-world riding needs. Whether you’re hitting motocross tracks or navigating backwoods trails, a properly matched pump ensures your 400EX delivers the 31 horsepower it’s famous for – mile after reliable mile.