Fuel Line Service on a 2017 Kymco MXU 500i
Shop parts for a 2017 Kymco MXU 500i ATV.
There is one step on the 2017 MXU 500i that has to happen before anything else, and it is the step most likely to be skipped. This machine is fuel injected, fed by a pump inside the tank, and the line running to the throttle body holds pressure long after the engine stops. You bleed that pressure first. Everything else in the job is ordinary hand-tool work, but that single sequence is what keeps the repair clean and safe.
Taking the Pressure Out of the System
Locate and remove the fuel pump fuse or relay, then crank the engine for a few seconds. It will fire briefly and stall as the circuit runs dry, which bleeds off most of the stored pressure. Turn the key off and disconnect the battery negative cable so the pump cannot be energized while a fitting is open. There is no petcock under the tank on an injected machine, so this electrical interruption is your shutoff, and line-clamping pliers handle any low-pressure section that would otherwise siphon.
With the pressure gone, remove the seat and enough plastic to see both the tank connection and the hose run forward. Take photos of the routing before disturbing it. On this four-wheel-drive chassis the hose passes front differential hardware and extra frame crossmembers that a two-wheel-drive quad does not carry, and reproducing that path exactly matters for clearance from moving parts.
What Wears a Fuel Hose Out
Rubber loses the plasticizers that keep it soft. They migrate out of the material and evaporate over the years, and what remains is a hard, glassy wall that cannot absorb movement. Heat cycling from the engine speeds that loss, and once flexibility is gone, engine vibration and chassis flex begin cracking the surface. Hot, dry regions accelerate the process by drawing moisture out of the hose wall from the outside inward.
Ethanol-blended gasoline handles the interior. It absorbs water vapor from the air, and the resulting mixture degrades the inner liner, which softens, swells, and releases fine debris toward the injector. Long stretches with that fuel standing in the system leave gum and varnish behind, restricting the passage and cementing the hose to its fittings. Because this line is pressurized rather than gravity fed, a wall thinned by that wear is under load every time the pump runs.
Warning Signs on an Injected Machine
- A fuel smell that peaks right after shutdown, while pressure is still trapped in the circuit
- A wet patch on the skid plate or floor, remembering that pressurized fuel frequently atomizes and evaporates before dripping
- Visible cracking, chalkiness, or a section that feels rigid and holds a crease when pinched
- Dust caked into a ring at a fitting, which is what slow weeping leaves after the fuel evaporates
- Bogging under load, hesitation on hard throttle, or a lean-running feel at higher revs
Restriction is easy to misattribute. The 499cc single asks for so little fuel at idle that a nearly blocked hose behaves normally at a standstill, only faltering when you put the machine to work.
Tools, Supplies, and Working Safely Around Fuel
- Rubber or nitrile gloves and eye protection
- An approved container to hold the fuel you capture
- Hose rated for fuel-injection pressure in the original inside diameter, not carburetor-grade hose
- Clamps matched to your fitting style, and a release tool if you find a quick-connect coupler
- Line-clamping pliers, since no petcock exists on this machine
- Socket set, screwdrivers, pliers, a razor knife, and plenty of rags
Take ventilation seriously for a real reason: gasoline vapor is heavier than air, so it collects at floor level and travels along the ground toward any ignition source. An open window at head height does very little, while a fully open garage door with a fan moving air low does a great deal. Outdoors is better still. Shut down anything with a standing pilot light, keep the battery disconnected while the system is open, keep hot lamps and chargers at a distance, and dry fuel-soaked rags outside rather than sealing them up.
Freeing the Aged Hose from Its Fittings
Position a drain pan under the work area and drape a rag over the first fitting you open, because even a bled circuit retains residual fuel. If a clamp secures the hose end, walk it well back along the rubber before disturbing the connection. If a self-locking quick-connect is used instead, depress the locking tabs squarely and pull the fitting straight off. Never lever it sideways, since a plastic collar that has aged in an engine bay for years will crack rather than release.
Old rubber bonds itself to a metal barb with dried varnish, so rotate the hose gently to shear that bond instead of pulling hard on the fitting. Where a section refuses to come loose, slit it lengthwise with the razor and peel it off. That protects the tank spigot and the throttle body inlet, both of which cost far more than a length of hose. As the line comes free, confirm the clearance points you photographed, particularly where it passes the front driveline.
Seating the Replacement and Testing Under Pressure
Cut the replacement to the same length as the original. Excess hose sags toward the front differential or rubs a frame tube raw over time, and a short piece keeps tension on both fittings whenever the engine rocks. Slide each end on dry until it bottoms past the raised bead.
Do not lubricate the fittings under any circumstances. Grease, oil, or silicone on a sealing surface gives pressurized fuel a route to migrate out from beneath the hose, and tightening the clamp harder will not close it. If the hose is too stiff to seat, hold the end in hot water for thirty seconds and it will slip on easily. Set new clamps just behind the bead at each end and tighten evenly until the hose stops rotating by hand. Where a self-locking quick-connect is used, push until the collar clicks and then tug firmly to confirm engagement, and add no clamp there. Clip the line back into its original guides, well away from exhaust heat and suspension travel.
Reinstall the pump fuse, Reconnect the battery, and cycle the key on and off several times without starting the engine. Each cycle runs the pump and pressurizes the line, giving you a dry, clean system to inspect. Feel around both joints and watch for beading or wetness on a rag underneath. Then start the engine, check again while it idles, rev it a few times, and only reinstall the plastics after several minutes of leak-free running. One last point for this platform: the fuel filter is part of the in-tank pump module rather than an inline piece on the hose, so if the 500i still runs starved after a clean install, that is where to look next.
Related Shopping Categories
Shop Fuel Lines for a 2017 Kymco MXU 500i ATV.
Shop Fuel Line Clamps for a 2017 Kymco MXU 500i ATV.
Shop Petcocks for a 2017 Kymco MXU 500i ATV.
Shop Fuel Filters for a 2017 Kymco MXU 500i ATV.
Shop Fuel Stabilizer for a 2017 Kymco MXU 500i ATV.
Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your ATV's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.