BART trains faced major delays Monday morning after a power problem halted normal service on one of the rail system’s busiest stretches, the transit agency said. BART reported a power issue between Powell Street and Embarcadero stations was disrupting service on the San Francisco Line in all directions, forcing the transit agency to sharply restrict transbay travel to the Yellow Line service. The Red line train service was fully suspended, and Blue line trains were operating only between Dublin/Pleasanton and West Oakland stations. BART did not immediately provide an estimate for when full service would resume. Commuters are advised to expect significant delays while crews work to resolve the issue.