1999 Polaris Sportsman 500 Fuel Shut Off Valve

Is your trusty 1999 Polaris Sportsman 500 sputtering on the trail, refusing to start, or leaving a tell-tale puddle of fuel on the garage floor? It’s a frustrating feeling when a simple, small part sidelines your entire machine, interrupting a weekend of work or fun.

You’ve come to the right place. We promise this guide will walk you through everything you need to know about the 1999 polaris sportsman 500 fuel shut off valve, a common but critical component. You’ll gain the expert knowledge and confidence to diagnose the problem, perform the replacement yourself, and get your ATV running like a champ again.

In this article, we’ll cover the valve’s function, the classic symptoms of failure, a step-by-step replacement process, and some pro tips for long-term care. Let’s get that rig back in action.

What is the 1999 Polaris Sportsman 500 Fuel Shut Off Valve and Why Does It Matter?

Think of the fuel shut off valve—often called a petcock—as the gatekeeper for your ATV’s fuel supply. Bolted directly to the bottom of your fuel tank, this manual valve controls the flow of gasoline from the tank to the carburetor.

It’s a surprisingly simple part with a massive job. Understanding its basic operation is the first step in any good diagnosis.

The Three Critical Positions: ON, OFF, and RES

Your fuel valve has a knob with three settings, and each serves a distinct purpose:

ON: This is the normal running position. It draws fuel from the tank through a primary pickup tube that sits slightly above the tank’s bottom.
OFF: As the name implies, this completely stops the flow of fuel. This is crucial for safety during transport, storage, or when performing maintenance.
RES (Reserve): When you run out of fuel in the ‘ON’ position, switching to ‘RES’ gives you access to a small, extra amount of fuel. It draws from a shorter pickup tube located at the very bottom of the tank, giving you just enough gas to get back to camp or your truck.

The primary benefits of 1999 polaris sportsman 500 fuel shut off valve functionality are control and safety. A working valve prevents your carburetor from flooding when the machine is off and allows you to safely shut off the fuel supply to prevent dangerous leaks.

Common Problems with 1999 Polaris Sportsman 500 Fuel Shut Off Valve: Symptoms of Failure

When this valve starts to fail, it can cause a range of confusing symptoms that might make you think you have a major engine problem. Fortunately, recognizing these signs is half the battle. This section serves as your initial troubleshooting checklist.

Here are the most common problems you’ll encounter:

Fuel Starvation (No Start/Stalling): The most common issue. Internal passages get clogged with sediment or ethanol gunk, restricting or completely blocking fuel flow. Your engine will crank but won’t start, or it might run for a few seconds and die.
Leaking Fuel: You might notice fuel dripping from the valve itself, either around the knob or where it mounts to the tank. This is usually caused by dried-out, cracked internal O-rings or a failed mounting gasket. Any fuel leak is a serious fire hazard and must be addressed immediately.
Carburetor Overflowing: If the valve fails internally and gets stuck open, it can continuously feed fuel to the carburetor. The carb’s float needle can get overwhelmed, causing fuel to spill out of the overflow tube.
Difficulty Turning the Knob: If the knob is extremely stiff or won’t turn at all, the internal seals have likely swollen or degraded. Forcing it can break the knob or the entire valve assembly.
Engine Sputtering at High RPMs: A partially clogged valve might allow enough fuel for the engine to idle, but it can’t keep up with the demand at higher speeds, causing the engine to sputter and lose power.

How to Diagnose a Faulty Fuel Shut Off Valve: A Step-by-Step Guide

Before you order parts, let’s confirm the fuel valve is actually the culprit. This simple diagnostic process requires minimal tools and will give you a definitive answer. Learning how to 1999 polaris sportsman 500 fuel shut off valve diagnostics is a key skill.

H3: Safety First: Pre-Check Essentials

Working with fuel is serious business. Always follow these safety rules:

Work in a well-ventilated area, preferably outdoors or with a garage door wide open.
Have a Class B fire extinguisher nearby.
Wear nitrile gloves and safety glasses.
Ensure there are no open flames, sparks, or heat sources nearby (no smoking, welding, or running heaters).
Disconnect the battery’s negative terminal as an extra precaution.

H3: The Simple Gravity Flow Test

This is the best way to check if fuel is actually getting through the valve. It’s the core of this diagnostic guide.

Locate the fuel line coming from the bottom of the petcock to the carburetor.
Place a clean, empty glass jar or a fuel-safe container under the valve.
Using a pair of pliers, squeeze the spring clamp on the fuel line and slide it up the hose. Carefully twist and pull the fuel line off the petcock’s outlet nipple.
Turn the fuel valve to the ‘ON’ position. You should see a steady, consistent stream of fuel flowing into your container.
Turn the valve to the ‘RES’ position. You should see the same steady flow.
Turn the valve to the ‘OFF’ position. The flow should stop completely, with no drips.

Test Results: If you get no flow, a weak trickle, or if it doesn’t stop in the ‘OFF’ position, you’ve confirmed the valve is bad and needs replacement.

Your Complete 1999 Polaris Sportsman 500 Fuel Shut Off Valve Replacement Guide

You’ve done the diagnosis and confirmed the problem. Now it’s time for the fix. This replacement is straightforward and a great project for a DIYer with basic tools. Follow these steps carefully for a leak-free repair.

Tools and Parts You’ll Need

New Fuel Shut Off Valve (Petcock) with Gasket/O-ring
Socket Set or Wrenches (typically 10mm)
Pliers (for hose clamps)
Clean Rags or Shop Towels
Fuel-Safe Drain Pan or Gas Can
Optional but Recommended: New fuel line and new hose clamps.

Step 1: Drain the Fuel Tank

You can’t remove the valve with a full tank of gas. The safest method is to run the ATV until the tank is nearly empty. Alternatively, you can use a siphon pump to transfer the fuel into an approved gas can.

Always drain the remaining fuel by performing the flow test from the previous section until the tank is empty.

Step 2: Remove the Old Fuel Valve

With the tank empty and the fuel line disconnected, use your socket or wrench to remove the two bolts holding the valve to the bottom of the fuel tank. Be prepared for a small amount of residual fuel to spill out—have a rag ready.

Once the bolts are out, the old valve will come right off. Take note of how the old gasket or O-ring was positioned.

Step 3: Clean the Mounting Surface

This is a critical step for preventing leaks. Use a clean rag to wipe down the mounting surface on the fuel tank where the valve sits. Make sure it is completely clean, dry, and free of any old gasket material, dirt, or grime.

Step 4: Install the New Valve and Reconnect

Place the new gasket or O-ring onto the new fuel valve. Position the valve against the tank and hand-thread the two mounting bolts to ensure they aren’t cross-threaded.

Tighten the bolts evenly, alternating between them to ensure the valve seats flush against the tank. Be careful not to over-tighten, as you can crack the plastic tank or the valve housing. Just get them snug and secure.

Slide your new (or old) hose clamps onto the fuel line, push the line securely onto the new valve’s outlet nipple, and position the clamp about a quarter-inch from the end of the hose.

Step 5: Refill and Check for Leaks

Before filling the tank completely, pour just a small amount of gasoline (a quart or so) back into the tank. Turn the valve to the ‘ON’ position and meticulously inspect for any leaks around the mounting bolts and the fuel line connection.

If everything is dry, you’re good to go! Fill the tank, start your Sportsman, and enjoy a job well done.

1999 Polaris Sportsman 500 Fuel Shut Off Valve Best Practices and Care Guide

A little preventative maintenance goes a long way. Following these 1999 polaris sportsman 500 fuel shut off valve best practices will help you avoid this problem in the future and keep your entire fuel system healthy.

The Importance of Regular Use and Quality Fuel

Letting an ATV sit for months is the worst thing for its fuel system. Use fresh, high-quality fuel whenever possible. Regularly cycling the valve from ON to OFF can also help keep the internal seals from getting stuck in one position.

Use Fuel Stabilizer for Storage

If you know you’ll be storing your Sportsman for more than a month, treat the fuel with a quality stabilizer. This prevents the gasoline from breaking down, varnishing, and gumming up the tiny passages in your petcock and carburetor. It’s the single best thing you can do for your fuel system’s longevity.

Eco-Friendly and Sustainable Fuel System Maintenance

Being a responsible rider includes caring for the environment. When performing this repair, practice sustainable 1999 polaris sportsman 500 fuel shut off valve maintenance by always using a drain pan to catch spills. Never pour old gasoline on the ground; take it to your local auto parts store or hazardous waste facility for proper disposal.

Choosing a high-quality replacement part also contributes to an eco-friendly 1999 polaris sportsman 500 fuel shut off valve approach, as it will last longer and create less waste over time.

Frequently Asked Questions About the 1999 Polaris Sportsman 500 Fuel Shut Off Valve

Can I just clean my fuel shut off valve instead of replacing it?

While you can sometimes disassemble and clean a valve clogged with debris, it’s often a temporary fix. The internal rubber seals and O-rings are usually the cause of failure, and they degrade with age. Given the low cost of a new valve, replacement is almost always the more reliable and safer long-term solution.

What’s the difference between the ‘ON’ and ‘RES’ (Reserve) settings?

Inside the fuel tank, the valve has two pickup tubes. The ‘ON’ setting uses a taller tube, leaving a small amount of fuel at the bottom. When you switch to ‘RES’, it draws from a much shorter tube, giving you access to that last bit of fuel so you can get back home.

Why is my ATV leaking fuel even when the valve is in the ‘OFF’ position?

This is a clear sign that the internal seals inside the valve have completely failed. The valve is no longer able to stop the flow of fuel, creating a dangerous leak. The part must be replaced immediately, and the ATV should not be started until it is repaired.

How tight should I tighten the bolts on the new valve?

Snug is the word. You want to create a good seal without damaging the parts. Tighten them evenly until they are firm. If you have a torque wrench and service manual, follow the manufacturer’s specification. If not, a “good and tight” feel with a small hand wrench is sufficient—avoid using power tools here.

Tackling repairs on your own machine is one of the most rewarding parts of being an off-road enthusiast. By following this guide, you’ve not only fixed a common problem but also gained valuable experience and saved yourself a trip to the shop.

Now that your fuel system is sealed and reliable, you can hit the trails with confidence. Stay safe, work smart, and get that Sportsman 500 back where it belongs—out in the dirt!

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Thomas Corle

Founder & Automobile expert at FatBoysOffroad

Automobile expert and off-road enthusiast, sharing in-depth knowledge of vehicles, gear, and adventures. Helping readers make smart decisions and enjoy the thrill of off-roading safely and confidently.