FedEx ( FDX - Get Report) says it will miss analysts' estimates for the current quarter and for fiscal 2009, as the continuing impact of high fuel prices and a weak economy drag on.

"We're pressured by serious economic difficulties," said CEO Fred Smith, on an earnings conference call. "Record high fuel prices and the weak U.S. economy dampened volume growth and substantially affected our bottom line."

Smith added that the "economic headwinds" the company is facing this year will continue into fiscal 2009. But he noted that results during this year and next "will be anomalies" that will "hopefully set the stage for fiscal year 2010."

Shares in FedEx were trading down 2.7% Wednesday at $82.02. Rival UPS ( UPS - Get Report) was off 2% at $66.03.

The package delivery company said it barely missed expectations for the fiscal fourth quarter, which ended May 31. Excluding one-time items, the company earned $1.45 a share. Analysts surveyed by Thomson Reuters had estimated $1.47.

Revenue rose 8% to $9.87 billion and was nearly $300 million more than had been anticipated. In the same period a year earlier, FedEx earned $1.90 a share.

Including a one-time charge of $696 million, or $2.22 a share, associated with the decision to pare back the Kinko's trade name, FedEx lost 78 cents a share. The net loss was $241 million, compared with net income of $610 million a year earlier.

Looking ahead, the company said high fuel prices and the related impact on surcharges is reducing demand for its services and cutting yields. Additionally, FedEx said, earnings are difficult to predict given fuel costs that are both high and volatile and an uncertain economic outlook. The company projected first-quarter earnings of 80 cents to $1 a share; analysts were estimating $1.27.

For fiscal 2009, FedEx is looking for a profit of $4.75 to $5.25 a share, whereas the consensus target is $5.92. The outlook assumes no additional fuel price increases or further weakening in the economy.

"We do expect conditions to remain extremely challenging," said CFO Alan Graf. "The current economic weakness will continue and the current level of fuel costs will not mitigate."

The company will hold capital expenses at about $3 billion, with much of it going to replace its aging Boeing 727-200s with fuel efficient 757s. "The 757 is 47% more fuel efficient," Graf said. "We can't get them acquired and modified as quickly as we would like."

The first 757 will enter service in September, and the first FedEx 777s will begin operating in 2010.

For the full year, net income fell 44% to $1.13 billion, and revenue rose 8% to $38 billion.