Democratic vice-presidential candidate Geraldine A. Ferraro today plunged into the Pacific Northwest on what she called "this campaign for economic justice" and was greeted with as much unalloyed exuberance as she has encountered.

Although this university town did not provide the largest crowd of her campaign, 3,000 persons showed up at an outdoor rally downtown to chant, "Gerry! Gerry!" while applauding virtually every line in her 20-minute speech.

"Mr. Reagan says America is back and standing tall. Well, I won't be satisfied until Eugene is also back and standing tall," Ferraro told the crowd in an address devoted largely to the theme of economic fairness. "It's not a complete recovery until the loggers and teachers and the others have also regained their jobs," she said.

Ferraro's strategists tried to put the best face on her lackluster sea-to-shining-sea Labor Day swing with Mondale, but several expressed chagrin privately at the series of snafus on the campaign's opening day. These included a tiny crowd for a parade in New York City, rain in Merrill, Wis., and sound-system problems in California.

"We didn't get a great start yesterday, as you know," a Ferraro aide said. "The nicest event was the Minneapolis refueling."

Asked whether she was discouraged because President Reagan drew comparatively larger crowds in campaign appearances in California on Monday, Ferraro said:

"Absolutely not . . . . We got there [the New York City parade] at 9 o'clock in the morning . . . and New Yorkers do not get out of bed and march at 9 o'clock in the morning, they don't get out and cheer at 9 o'clock on a holiday."

Earlier today near San Diego, Ferraro toured Kahl Scientific Instrument Corp., a small manufacturer and exporter, where she said, "Since Mr. Reagan [has been] in office, we've seen more small-business closings than at any time since the Great Depression."

John Sasso, Ferraro's campaign manager, said the visit was to emphasize that "small businessmen and women are a very important part of the Democratic coalition. I don't think that they feel that Mr. Reagan's economic policy has been fair to them."

Although Ferraro said federal budget deficits and the overvalued dollar have hurt small-business efforts to market products overseas, she also said Mondale "does not support a commodity by commodity or industry by industry protectionist attitude."

Steven Engelberg, Ferraro's issues director, said Mondale and Ferraro have supported domestic-content legislation tailored to aid the automobile industry. Mondale has said the measure is not protectionist but is a lever to make other nations, notably Japan, abide by international trade agreements.

To redress the U.S. trade imbalance, Engelberg added, the two candidates favor reduced deficits, greater federal assistance in promoting exports, a greater effort to make domestic industries more competitive and "a level playing field" on which all nations abide by the same trading rules.