(Recasts first paragraph; adds details of accusations, dismissal of claim related to vehicle battery)
By Jonathan Stempel
July 19 (Reuters) - A Florida jury found electric car maker Tesla Inc 1% negligent in the death of an 18-year-old man whose Model S sedan slammed into a concrete wall after the car's speed limiter had been deactivated, with the teenager and his father found to be 99% at fault.
Monday's verdict by a Fort Lauderdale federal jury came in what lawyers for James and Jenny Riley, whose son Barrett died in the crash, called the first trial against Tesla over an accident involving its vehicles.
Barrett Riley had been driving at 116 miles per hour (187 kph), on a curve with a posted 25 mph speed limit, on May 8, 2018, when he lost control of his 2014 Model S while trying to pass another vehicle, causing a fire.
Another passenger also died while a third occupant survived.
Riley's parents said the crash occurred after a Tesla technician, without their knowledge, disabled a device that had been installed at their request and which capped the Model S's speed at 85 mph (137 kph).
The jury found Tesla 1% negligent, Barrett Riley 90% negligent, James Riley 9% negligent and Jenny Riley not negligent in Barrett Riley's death.
The jury said James and Jenny Riley suffered a respective $4.5 million and $6 million of damages for pain and suffering, which the judge can reduce based on the negligence findings.
Lawyers for Tesla did not immediately respond on Tuesday to requests for comment.
Tesla, headed by billionaire entrepreneur Elon Musk, had said that Barrett Riley's recklessness caused the crash and his parents should have taken away the keys after his March 2018 speeding ticket for driving at 112 mph (180 kph).
It also said Barrett Riley tricked the technician into disabling the speed limiter.
The parents said a design defect in Tesla's lithium-ion battery cells and battery pack contributed to the fire, but a judge on June 29 dismissed that claim.
In a statement, the Rileys' lawyer Curtis Miner said they were pleased with the negligence finding, and hoped the case would help prevent other accidents and save lives.
Tesla has faced a variety of lawsuits and regulatory probes over crashes tied to its Autopilot feature. That feature was not at issue in Barrett Riley's crash, court records show. (Reporting by Jonathan Stempel in New York; Editing by Howard Goller and Leslie Adler)