How to Change the Fuel Line on a 2008 Suzuki King Quad 400AS 4X4 Auto

Shop parts for a 2008 Suzuki King Quad 400AS 4X4 AUTO ATV.

The first thing to establish on any fuel line job is what kind of system you are actually dealing with, because that decision drives everything that follows. On the 2008 King Quad 400AS, the answer is straightforward and it works in your favor.

Identifying What Feeds This Engine

The 400AS runs a carbureted 376cc single paired with the automatic CVT drivetrain, which means a petcock valve sits at the base of the fuel tank and gravity feeds the carburetor through a length of soft rubber hose. There is no fuel pump to disable, no pressurized rail, and no electrical connector to unplug before you open a fitting. Flip the petcock to OFF and the supply stops — that is the entire shutoff procedure. You also get a serviceable float bowl drain screw at the bottom of the carburetor, which makes emptying residual fuel out of the low point genuinely easy.

Worth noting on this machine: it is a 4X4 chassis. The front differential housing, its driveshaft, and the extra frame crossmembers that come with four-wheel drive take up room a two-wheel-drive quad leaves open, so the hose is routed with tighter clearances and secured by clips that keep it away from rotating and hot components. Pay attention to that routing on the way out, because putting the new hose back along a slightly different path is how a line ends up chafing.

What Makes Rubber Hose Wear Out

Fuel hose degrades in two directions at once. Heat cycles from the engine and years of air exposure leach the plasticizers out of the rubber, so the hose gradually turns from pliable to stiff to brittle. In dry, low-humidity climates that hardening accelerates, since arid air constantly draws moisture out of the hose wall. Once the surface is hard, ordinary chassis flex over washboard and rock is enough to work fine cracks into it.

Ethanol-blended gasoline handles the other half of the job. Alcohol in the fuel attracts moisture and slowly breaks down the hose liner from within, and a King Quad that sits for months with that fuel standing in the line will develop gum and varnish deposits at the barbs while the inner wall softens. You can end up with a hose that passes a visual inspection while restricting flow and shedding particles toward the carburetor jets.

Signs Your Line Needs Attention

  • A fuel puddle or wet patch on the skid plate or garage floor after the quad has been parked
  • A strong, persistent gasoline smell around the tank and front rack area
  • Visible cracking, a chalky grey surface, or a section that feels rigid when pinched
  • A dirt-caked ring of dried fuel residue at either barb, which marks a slow seep
  • An engine that bogs when you open the throttle, hesitates at steady speed, or acts starved for fuel with plenty in the tank

The running symptoms deserve a mention on their own. A gravity-fed carburetor has very little pressure behind it, so even a partially collapsed or gum-restricted hose can starve the float bowl under sustained load. If the machine pulls better on reserve than on the main position, the supply path is where you should be looking.

Setting Up: Tools, Parts, and Ventilation

Have this ready before you start: nitrile or rubber gloves, safety glasses, a lidded fuel-rated container, a drain pan, replacement hose in the correct inside diameter, new pinch or worm-gear clamps, pliers, a flat-blade screwdriver, a razor blade, a socket set for the seat and body panels, and clean rags.

Handle the fuel with real care. Gasoline vapor is heavier than air and settles at floor level where it can find an ignition source you never thought about, so work outdoors or with the garage door fully open rather than trusting a small window. Disconnect the battery, kill any furnace or water heater pilot in the space, and keep the area clear of grinders, torches, and anything smoldering. Mop up spills right away instead of letting them evaporate off the concrete for hours.

Removing the Old Hose and Fitting the New One

Turn the petcock to OFF, then pull the seat and the plastic panels covering the tank so you can see both ends of the run. Slide the pan under the carburetor and open the float bowl drain screw to empty the bowl. Walk both clamps back along the hose with pliers before you disturb either fitting.

Break the varnish bond with a gentle quarter-turn twist rather than a straight pull. If a hardened end will not budge, split it lengthwise with the razor and peel it off in two pieces — that protects the petcock spigot and the carburetor inlet, which are the expensive parts in this equation. On this 4X4 frame, trace the hose through its clips and past the front driveline clearance points and photograph it before it comes fully free.

Cut the replacement to the same length as the old piece, no longer. Push each end all the way onto its barb until it passes the raised bead, and install it completely dry: grease, oil, or silicone on a sealing surface creates a leak path and lets the hose walk off under vibration. Dip a stiff hose end in hot water for thirty seconds if it fights you. Set new clamps just behind each bead, snug them evenly, and restore the hose to its original clips so it clears the exhaust, the front driveshaft, and the steering.

Proving It Is Sealed Before You Ride

Turn the petcock back to ON and let a full tank sit on the connections for a few minutes with a dry rag under each joint. Static gravity pressure will reveal a poor seal quickly. Start the engine, let it idle, and go over both fittings again by hand and by eye, then take a short slow lap and recheck once everything is warm. Only when both ends stay dry and the fuel odor is gone should the panels and seat go back on.

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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.