Problems with the Model X could hurt production of the current Model S sedan, because the two vehicles will be manufactured on the same assembly line at Tesla’s factory in Fremont, Calif.

Image Elon Musk, chief executive of Tesla Motors. Credit... Ringo H.W. Chiu/Associated Press

“We do think it’s going to be quite a challenging production ramp” with the new S.U.V., Mr. Musk said on Wednesday in a conference call with investors. “We don’t want to drive to a number that’s greater than our ability to deliver high-quality vehicles.”

He called the new Model X “a particularly challenging car to build.”

Tesla met its target for second-quarter deliveries, however, with 11,532 vehicles transferred to customers.

Asked whether the reduced outlook for deliveries would prevent Tesla from turning cash flow positive by the end of the year, Deepak Ahuja, the chief financial officer, said it would be “close to call,” and might take until the first quarter of 2016 to achieve that goal.

Tesla has also been spending heavily as it prepares to introduce the Model X, and develops a more affordable sedan, the Model 3. In the second quarter Tesla spent a total of $405 million on capital expenditures, contributing to the continuing losses.