Auto-Train Corp. said it will end its trains from Louisville, Ky., to Sanford, Fla., effective Sunday rather than cut back to once-a-week service as previously planned.

Auto-Train officials in Washington said the Louisville route had lost money under two different operating arrangements and showed little prospect of turning a profit with reduced service.

For the past six months Auto-Trains from Louisville had been towed behind Amtrack's Floridian, which runs from Chicago to Florida via Louisville Auto-Train said the route had been operating at about 40 per cent of its capacity of 100 passengers and 32 automobiles a day. Auto-Train passengers rode in separate cars with no access to Amtrack cars.

An Amtrack spokesman said the joint operation experiment had failed to boost its revenues on the route, which lost about $62 million in direct costs last year.

Amtrack and Auto-Train officials, however, said failure of the Louisville-Florida run did not rule out future joint operations.

Auto-Train had announced a month ago the joint route would be ended, but said it planned to operate its own trains over the route once a week in each direction. Before starting the joint direction.Before starting the joint service, Auto-Train had used its own locomotives to pull trains on that route, which was started in May 1974.

Two derailments on the Lousville run last year forced suspension of service for several weeks; the disruption further discouraged traffic.

Losses on the Louisville route have hurt Auto-Train earnings in recent years.

The company's annual report for the fiscal year ended April 30 has not yet been issued, but Eugene K. Garfield, chairman and president, earlier predicted a $150,000 loss for the year.

Auto-Train officials said there is a possibility limited service to Louisville might be restored during the winter tourist season.

Auto-Train laso has asked the Interstate Commerce Commission to approve a joint operation with Eastern Airlines. Passengers would fly to Florida while their cars take the train from Louisville or Auto-Train's terminal at Lorton, Va.