Water and fuel don’t mix—at least, they shouldn’t. But sometimes, whether due to bad fuel, condensation, or a small leak, water can find its way into your fuel tank. The results? Engine problems, performance issues, and potential long-term damage.
If you’ve ever wondered what happens when water gets into your fuel and how to fix it, this article will break it down for you.
How Does Water Get Into Your Fuel?
Water can enter your fuel tank in several ways, and while a few drops won’t immediately destroy your engine, too much can cause serious trouble. Here’s how it typically happens:
- Bad Fuel from the Pump – Sometimes, fuel from a gas station may already be contaminated with water due to improper storage or old underground tanks.
- Condensation in the Tank – If you live in an area with fluctuating temperatures, condensation can form inside your fuel tank, especially if it’s not full.
- Damaged Fuel Cap or Tank Leak – A loose or damaged fuel cap or a crack in the fuel system can let in moisture, especially after heavy rain or washing your car.
What Happens When Water is in Your Fuel?
1. Engine Misfires and Poor Performance
Water doesn’t combust like gasoline or diesel. Instead, it interrupts the combustion process, causing engine misfires, hesitation, and loss of power. You may feel your car struggling to accelerate or sputtering when idling.
2. Hard Starting or No Start at All
If enough water is in your fuel, it can make starting your engine difficult. Water is heavier than gasoline, so it tends to settle at the bottom of the tank—right where your fuel pump pulls from. If water gets sucked into the system, your engine may refuse to start.
3. Rust and Corrosion in the Fuel System
Water and metal don’t mix well, and if water sits in your fuel system for too long, it can lead to rust and corrosion. This can damage fuel injectors, fuel lines, and even the fuel tank, leading to expensive repairs.
4. Clogged Fuel Filters
Fuel filters are designed to catch impurities, but they can only handle so much. Water contamination can overwhelm the filter, causing it to clog faster and restrict fuel flow, leading to stalling and poor engine performance.
5. Fuel Injector Damagea
Modern fuel injectors are highly sensitive and require clean fuel to function properly. If water enters the injectors, it can cause erratic fuel spray patterns, poor combustion, and long-term damage.
How to Tell if There’s Water in Your Fuel
Not sure if you have a water contamination problem? Look for these warning signs. Your engine may feel rough, especially when starting. If water affects combustion, your car’s computer may trigger a warning. Excess water in the fuel can create white smoke from your tailpipe. The car struggles to accelerate or feels sluggish. If your engine isn’t running efficiently, you’ll burn more fuel than usual.
How to Fix Water in Your Fuel
Fuel additives like Heet or ISO-HEET are designed to absorb water in gasoline. These work well for small amounts of water and prevent freezing in colder temperatures. For larger amounts of water contamination, the best solution is to drain and replace the fuel. This may require removing the fuel tank or using a fuel siphon.
If water has passed through your fuel system, your fuel filter may be clogged. Replacing it ensures clean fuel flow. If water keeps getting into your fuel, inspect your fuel cap, fuel lines, and tank for cracks or leaks.
How to Prevent Water in Your Fuel
Prevention is always better (and cheaper) than fixing a contaminated fuel system. Here’s how to avoid the problem:
Less empty space in your tank reduces condensation. Avoid old or low-quality gas stations with poorly maintained fuel tanks. Make sure your fuel cap seals properly to keep moisture out. If your car sits unused for long periods, a fuel stabilizer can prevent water buildup.
Water and fuel don’t mix, and if water gets into your tank, it can lead to engine trouble, poor performance, and costly repairs. If you notice any signs of contamination, act quickly by using a fuel additive or draining the tank.