A Prior Lake man's attempt to run from San Francisco to New York City in world-record time stalled out in Utah, a little less than 700 miles into what was meant to be a 3,100-mile run.

Steve Knowlton, 47, ended his run late Saturday, on Day 15, at Skull Pass in central Utah. His supporters said he was having difficulty absorbing nutrition, and feet problems were more than he could endure.

Inspired to raise money and awareness about Asperger's syndrome, a high-functioning form of autism, Knowlton left the Bay Area on May 18 with a plan to average 70 miles a day and reach the Big Apple within 45 days of starting.

The San Francisco-to-New York City record holder remains Frank Giannino Jr., who in late 1980 covered 3,103 miles in 46 days, 8 hours, 36 minutes. He averaged 66.79 miles a day.

Knowlton, who has completed more than 45 marathons and seven ultramarathons, ran alone in 2010 from Seattle to Key Largo, Fla., in 100 days, averaging 37 miles per day and pushing a jogging stroller he estimates weighed 100 pounds for the majority of the 3,700-mile trip. The run was to highlight Crohn's disease, a chronic inflammatory bowel ailment that struck Knowlton when he was in high school.