NASHVILLE, Tenn. -- Most of middle Tennessee's gas stations have added ethanol to their gasoline, but if it’s not done right, cars could suffer.

Video: Some Ethanol Gas Could Be Watery

In the last year or so, the Tennessee Department of Agriculture has received about 100 complaints, and 86 percent of those were from people who believe the ethanol-blended fuel may be resulting in water in their engines.

It’s a problem the state is aware of and trying to crack down on.

Danny Sutton checks on 6,000 gas pumps in Nashville every year. He said that lately, the most common ailment he's hearing about is hydration.

"Ethanol invites water to stay in gasoline," he said.

So if tanks aren't properly prepped and cared for, water can end up in the engine, and people could end up with an expensive problem.

"My son's car has sputtered, and he swears it was because of the ethanol,” said Diane Gates. “I didn't even realize that they were putting it in the gas until all of a sudden, I looked at it and it says, 'Contains ethanol.' And I says, 'Oh.'"

With ethanol-blended fuels, a tank is only allowed to hold a quarter of an inch of water. Sutton does tests and said those that fail will be stopped so water can be pumped out.

"I'm going to stop sell whatever grade gasoline that is," he said.

So far, Sutton said, that's happened four or five times in middle Tennessee in the last year.

Most stations have alarms alerting owners if too much water is in the tanks.

State inspectors said the No. 1 violation they're finding in regards to ethanol gas at stations is that stations aren't always labeling their pumps as having ethanol.

Officials said the only cars that should have any potential problems with ethanol fuel are those made before 1980.

If you have a complaint about a gas station, contact the Department of Agriculture at 800-OCTANE-1.