20:33 02-11-2025

Water in the fuel tank: signs, diagnosis, and prevention

Water in the fuel tank is a small issue with big consequences — it can sideline an otherwise healthy engine. As auto expert Dmitry Novikov explained to 32CARS.RU, moisture corrodes key parts of the fuel system — the pump, injectors, and filters — and throws the combustion process off balance.

The main culprit is condensation. When humid air inside the tank cools down, droplets form on the walls and settle at the bottom. Water can also sneak in through a faulty fuel cap, during refueling in the rain, or together with poor-quality fuel from a filling station.

You can spot trouble by a cluster of telltale symptoms: hard starts, hesitation under acceleration, a noticeable drop in power, or a glowing “Check Engine” light on the dash. Brushing these signals aside isn’t worth the gamble — corrosion doesn’t pause, and metal parts along with seals suffer first.

There’s a straightforward way to confirm the problem: use a dedicated indicator that reacts to water. If moisture is present, the sensible course is to drain the fuel completely, flush the tank, and replace the filter. To keep the issue from returning, stick to trusted fuel stations and make sure the fuel system remains properly sealed. In practice, a bit of vigilance here pays off quickly.