Why Your 1998 Foreman 400 4x4 Needs a New Fuel Line and How to Fit One
Shop parts for a 1998 Honda TRX400 Foreman 4X4 ATV.
Almost nothing on a 1998 TRX400 Foreman 4x4 wears out purely from sitting. The fuel hose is the exception. It degrades on a calendar rather than an hour meter, which means a low–hour machine that has spent most of its life parked can easily have worse rubber than one that works every week. Understanding the mechanism explains why the fix is cheap insurance.
What Happens to Rubber Over Twenty Five Years
Fuel hose is flexible because of plasticizing compounds blended into the rubber when it was made. Those compounds slowly migrate to the surface and evaporate, and there is no way to put them back. Heat cycling from the air–cooled 395cc single accelerates the loss with every warm–up and cool–down. The hose passes through predictable stages: it stops flattening easily under your fingers, the surface dulls to a chalky gray, and then hairline splits appear on the outside of the tightest bend in the run. Once that happens, engine vibration and frame flex convert a crack into a weep and eventually into a steady drip.
Where you live matters. Dry inland and high–desert conditions shorten the timeline because low ambient humidity pulls moisture out of the rubber wall from the outside inward. Meanwhile ethanol–blended pump gas works from the opposite side. Fuel standing in the hose through a long idle period draws in atmospheric water and degrades the inner liner, releasing fine particles downstream and leaving gum and varnish in the petcock screen and the carburetor's small passages. A hose can be hardening outside while breaking down inside, which is exactly why appearance alone is a poor guide on a machine this old.
Reading the Foreman's Complaints
- Fuel puddling on the skid plate or floor beneath the tank or carburetor after a period parked
- A gasoline smell that persists in a closed building long after shutdown
- Visible cracking, crazing, or a dried gray finish on the hose
- Rubber that feels rigid rather than springy when squeezed
- Bogging under load, lean surging on climbs, or a stall that mimics an empty tank
- A caked ring of dirt at a fitting where fuel has seeped and evaporated repeatedly
Sorting the Fuel System Before You Order Parts
This Foreman is carbureted. Gasoline flows from the tank to the carburetor by gravity through a mechanical petcock with off, on, and reserve positions, and no part of the hose is pressurized. That single fact defines the procedure. On a fuel–injected quad the first move would be pulling the pump fuse or relay and cranking until the engine stalls to bleed off pressure, its filter would sit inside the tank as part of the pump assembly, and some of its connections would be self–locking quick–connect couplers requiring no clamp. Here you have a two–finger shutoff, plain clamped barbs, and a float bowl drain screw for emptying the low side on your terms.
On the 4x4 layout, the front differential and propeller shaft take up room a two–wheel–drive machine leaves open, so the hose runs through tighter clearance and its retaining clips genuinely matter for keeping it off the driveline and away from the exhaust. Photograph the routing before you disconnect anything.
Getting Organized and Staying Safe
Have on hand fuel–rated hose in the original inside diameter, new clamps of the same style, nitrile gloves, eye protection, a drain pan, a sealed approved fuel container, a flat–blade screwdriver, basic sockets, a sharp utility blade, rags, and good light.
The safety concern here is real and specific. Gasoline vapor is heavier than air, so in an enclosed garage it sinks and pools across the floor precisely where you kneel while working. Move the machine outdoors if you can. Otherwise open the door fully and set a fan on the ground to push air out of the space. Kill pilot lights on nearby appliances, relocate battery chargers and power tools, and disconnect the negative battery cable before you open a fuel fitting.
Removal and Installation Step by Step
Rotate the petcock to off. Pull the seat and the tank cover to expose both hose ends. Slide the pan under the carburetor, back out the float bowl drain screw, and let the bowl and the hose drain, then retighten the screw. Move both clamps back along the hose until they clear their barbs.
Twist the hose on each fitting to break the varnish bond rather than pulling straight off, then work it away in stages. Hardened rubber will bend the petcock spigot or crack the carburetor inlet before it lets go, so slit anything truly seized lengthwise with the blade and peel it off in halves. Trace the old line through its clips as it comes out.
Cut the replacement to match the removed hose laid out flat, adding no extra length. Slide the clamps on before installing, then press each end fully onto its barb until it seats against the shoulder. Assemble dry — grease, oil, and silicone all leave a film that gives fuel a route to migrate out under a clamp. Warm water is the correct way to soften a stubborn hose end. Position each clamp just behind the raised bead on its fitting and tighten evenly, firmly but without cutting into the rubber, then route the hose back through its original clips.
Confirming It Is Dry Before You Ride
Reconnect the battery and turn the petcock on. Gravity feed fills the hose immediately, so stand and watch both joints for a full minute; a poor seal shows itself fast as a bead forming at a clamp edge. Wipe both fittings with a clean dry rag and inspect a second time, since a thin film of residual fuel from the removal can be mistaken for a leak. Start the engine and let it idle several minutes, then run a flashlight over both connections while everything is hot and vibrating. Only when both stay completely dry should the tank cover and seat go back on. Check the ground under the Foreman after the first working ride as a final confirmation.
Related Shopping Categories
Shop Fuel Lines for a 1998 Honda TRX400 Foreman 4X4 ATV.
Shop Fuel Line Clamps for a 1998 Honda TRX400 Foreman 4X4 ATV.
Shop Petcocks for a 1998 Honda TRX400 Foreman 4X4 ATV.
Shop Fuel Filters for a 1998 Honda TRX400 Foreman 4X4 ATV.
Shop Fuel Stabilizer for a 1998 Honda TRX400 Foreman 4X4 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.