Changing the Fuel Line on Your 2010 Big Bear 400 4x4
Shop parts for a 2010 Yamaha Bigbear 400 4X4 ATV.
What the Job Involves
On a 2010 Big Bear 400 4x4, the entire fuel delivery path consists of a manual petcock at the tank, one rubber hose, and a carburetor inlet. Fuel moves by gravity alone. That means replacing the line requires no diagnostic equipment, no pressure relief procedure, and no specialty fittings — just a shutoff at the petcock, careful removal, and a properly seated new hose. An owner comfortable pulling a seat and a couple of body panels can finish the work in an afternoon and be confident in the result.
Carbureted Means a Simpler Opening Sequence
It is worth being explicit about the fuel system, because it dictates the first several steps. This Big Bear is carbureted, so a manual petcock controls flow and rotating it to off kills the supply instantly. Nothing in the line stays pressurized after shutdown, and there are no plastic quick-connect couplers to unlatch. Fuel-injected quads work the other way: they lack a petcock entirely, retain pressure in the line, and demand pulling the pump fuse, running the engine dry, and clamping the hose shut before disconnection. Your carburetor also provides a float bowl drain screw, which is the neatest possible way to empty the last of the fuel out of the system.
The Slow Death of a Fuel Hose
Age, not mileage, is what finishes rubber fuel line. Repeated heating and cooling gradually strips out the plasticizers that keep the hose flexible, and once the wall goes hard, everyday chassis vibration cracks it at the tightest bends. Arid environments make this happen sooner, since dry air continuously pulls moisture from the outer surface.
The fuel itself contributes from inside. Ethanol blends attract water, and a hose sitting full through long inactive stretches slowly loses its inner liner to that mixture while accumulating gum and varnish. Those deposits narrow the bore and plug the petcock screen, which is why an old line can restrict flow noticeably even when the exterior still looks sound.
Symptoms to Watch For
- Gasoline collecting on the skid plate or spotting the floor after an overnight sit
- A persistent fuel smell around the machine with the petcock in the off position
- Surface cracking, chalkiness, or a hardened section that holds a dent when squeezed
- Bogging while lugging up a hill, hesitation off idle, or a lean feeling that mimics a dry tank
- Caked dirt rings at the fittings, left by fuel that seeped and dried repeatedly
Because the hose ages uniformly from end to end, one bad spot is your signal to replace the entire run instead of patching a section.
Gear, Parts, and Ventilation
- Nitrile or rubber gloves plus eye protection
- An approved fuel container and a wide catch pan
- New fuel line matched to the original inside diameter, cut long for trimming
- Fresh spring clips or small worm-gear clamps
- Flat-blade screwdriver, needle-nose pliers, razor knife, clear tube, and rags
Handle the fuel side of this job with real care. Move the quad outdoors or open the overhead door completely, since gasoline vapor is heavier than air and settles into a layer at floor level where a high window does nothing for you. Shut off pilot lights, unplug shop heaters, and keep grinders, torches, and open flame out of the area entirely. Gloves stay on the whole time because raw gasoline defats skin and carries dissolved contaminants through it.
Removing the Old Line
With the petcock off, lift the seat and pull the panels blocking access to the tank outlet and the hose run. Slide the pan into place, then open the float bowl drain screw and route the carburetor's contents into your container through the clear tube. That step alone captures most of the fuel that would otherwise end up on the frame.
Work both clamps well back along the hose until the barbs are clear. Old rubber typically bonds to the fittings with dried varnish, so twist the hose to break that seal rather than pulling straight out. If it refuses to release, split it lengthwise with the razor and peel it away in strips instead of prying on the petcock spigot or the carburetor inlet. Take note of the routing before the second end comes off. As a 4x4, this Big Bear guides its hose past front differential hardware and additional frame crossmembers a 2x4 chassis does not have, and matching that path keeps the new line away from heat and rotating parts.
New Hose In and Leak Verification
Cut the replacement to the length of the original. Extra hose droops into the frame and abrades through, while a short piece pulls sideways on the barbs until one lets go. Seat each end past the raised bead and install it dry, with no grease, oil, or silicone anywhere near the fittings, since any lubricant film gives fuel a route out from under the clamp. A brief dip in hot water softens a stubborn end enough to slide on by hand. Set new clamps just behind the bead at both connections, snug them evenly without crushing the wall, and clip the line into its factory guides clear of exhaust heat and steering travel.
Close the drain screw and open the petcock. Gravity fills the hose immediately, so watch both joints for a full minute before doing anything else. Wipe them dry, inspect a second time, then start the engine and let it idle several minutes for a final check under vibration. Since this Big Bear is carbureted rather than injected, its debris screen sits inside the reachable petcock instead of in the tank on a pump module, so continued lean running after a clean install points to that screen and the carburetor jets.
Related Shopping Categories
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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.