ST. JOHNS COUNTY, Fla. -

Three men were arrested Saturday on grand theft charges after deputies said they pumped more than 1,000 gallons of diesel fuel and only paid for 140 gallons.

An employee of the Flying J truck stop at State Road 206 and Interstate 95 who is familiar with the pumping of diesel fuel became suspicious of the amount of time the trio, Carrillo Rayner, 30, Juan Fernandez, 47, and Henry Morales-Rosales, 33, spent pumping, deputies said. The employee thought it was inconsistent with the amount of fuel that was paid for.

An investigation found that the suspects were somehow able to unlock the gas pumps, deputies said. In doing so, they disturbed the wiring harness that connected the pumps with the circuit boards.

At that time, the pump stopped displaying inside the building.

The three are charged with pumping 900 gallons of diesel, at $4.01 per gallon, but only paying for 140 gallons.

Rayner, Fernandez and Morale-Rosales were booked into St. Johns County jail and all tractor-trailers were seized.