TORONTO, NOV. 26 -- Stanislaw Tyminski, the enigmatic Polish-Canadian entrepreneur who toppled a Polish government and forced Solidarity union leader Lech Walesa into a runoff in Poland's presidential election, decided to enter the race in the same impulsive way that he joined Canada's fringe Libertarian Party and quickly became its leader, political associates here said today.

"Stan was driving around in his Mercedes one day when he heard me doing a radio interview at a protest we were holding in front of the Revenue Canada building," Daniel Hunt, the Libertarians' Ontario chairman, said in recalling his first meeting in October 1989 with Tyminski. Two or three weeks later, Hunt recalled, the two men met, and last May 21 Tyminski was elected leader of the ultraconservative 3,500-member party.

Roma Kelembet, who is second-in-command of the national Libertarian movement, recalled that she had lunch with Tyminski in September, soon after he had returned from a visit to Poland, where he had arranged for the private publication of his book, "Sacred Dogs," a political manifesto espousing economic self-reliance and individual liberty.

"A couple of days later, he said, 'You know, one of the {Polish} unions called and asked me to stand in the presidential elections,' " Kelembet said. "I said that it was something to think about, and while he was driving me home he said, 'If I could just turn 10 Poles to a free-market economy, I'd be happy and successful.' With those thoughts in mind, he flew to Poland the next day and became a candidate."

The Libertarians, who advocate an unfettered free-enterprise system, minimal government and no taxes, have never won more than 0.9 percent of the vote in a Canadian national election. Tyminski got nearly 24 percent in Poland's election, winning more votes than all Canadian Libertarian candidates combined have ever won.

After Tyminski finished ahead of Prime Minister Tadeusz Mazowiecki in Sunday's first-round balloting, a number of Canada's 150,000 Polish-born citizens said they thought the 42-year-old self-made millionaire was as little known here as he was in Poland.

"He's still a mystery. We're asking ourselves, 'Who is Tyminski? Where did he come from?' " said Janusz Sukiennik, editor-in-chief of the Toronto Polish-language biweekly Zwiazkowiec, the newspaper of the Polish Alliance of Canada.

"We are shocked. I'm as surprised as you are. He's a man of character and integrity, but to be leader of a country takes more than that. He should be known and, well, checked," said Sukiennik.

Other Polish-Canadian activists described Tyminski as an eclectic and an ideologue, driven by ambition and nervous energy and deeply motivated by Polish nationalism and a hatred for communism and any form of government intervention.

The Polish Alliance did not endorse any candidate in Sunday's election, and the Polish consulate here said that Tyminski ran a distant third in absentee balloting by Polish Canadians. In Toronto, which has the nation's largest concentration of Polish-born Canadians, Mazowiecki received 2,134 votes, Walesa 2,087 and Tyminski 469.

Sukiennik, who said he had met Tyminski once, said that the ubiquitous businessman, who holds Peruvian citizenship as well as Canadian and Polish, was not active in any of Canada's Polish organizations and apparently had not contributed to groups connected with Polonia, as the immigrant community is known.

Stanley Orlowski, past president of the Canadian Polish Congress, said, "We see thousands of people every month, but somehow I never met him."

According to friends, business associates and Libertarian Party colleagues, Tyminski led a classic rags-to-riches life during his two decades in Canada. Disheartened by his prospects in communist Poland, he emigrated in 1969, leaving behind his mother and a sister in a Warsaw suburb. Following a brief stay in Sweden, he came to Canada, where he studied computer science and founded a small company in the Toronto suburb of Mississauga, Transduction Ltd., which specializes in machine control systems and which reportedly has annual sales of about $10 million.

In late 1981, Tyminski took a vacation in Peru, where, according to acquaintances, he experienced a spiritual transformation while traveling with Indian tribesmen in the Amazon jungle. He stayed in Peru for four years, founding a cable television company, TVS Iquitos, opening a restaurant and operating a farm.

He also met his second wife, Gracelia, 30, who practices iridology, whose adherents profess to be able to determine the soundness of the body by studying the iris.

"He had a spiritual rejuvenation in the jungle. . . .He apparently was a changed man when he returned here," Hunt said.

Returning to Toronto in 1985, Tyminski continued to build his network of companies here and in Florida and Peru, business associates said. But he maintained a relatively modest lifestyle, living in an unpretentious two-story house in the middle-class neighborhood of High Park, sending his children to public schools and trading his Mercedes 450SL for a Chrysler minivan.

Associates recalled that he began writing his collection of political thoughts while spending the summer of 1989 at a strawberry farm he operates near Acton, Ont., north of Toronto, but that he never discussed specific political ambitions.

They said when he returned to Poland in September to promote his book, with only one suit and a battered suitcase, he probably did not go with any firm plans to run for the presidency.

"Before he left, we were discussing his standing in the federal election in Canada, but I never guessed he would actually do it in Poland. But that's the way Stan is. You never know what he's going to do," Kelembet said.