Much of the trauma of the Abscam investigation subsided on Capitol Hill 11 days ago with the resignation of Sen. Harrison A. (Pete) Williams Jr. (D-N.J.), last of seven members of Congress convicted of bribery and related offenses. But repercussions continue.

So far courts have upheld the tactics used by the FBI in obtaining convictions of the six congressmen, one senator and state and local officials. But those tactics have left innocent people with reputations or businesses injured as a result of Abscam. Some of Abscam victims have filed lawsuits against the FBI and others are considering following suit.

And in Congress sentiment is growing for a thorough investigation of the FBI's methods, including how the FBI chose targets, how much freedom the bureau gave its middlemen, especially convicted felons, and what safeguards the FBI used to protect innocent people. Some of those innocent people are expected to tell their stories.

For Rep. William J. Hughes (D-N.J.), one of the congressmen mentioned on the fringes of Abscam, the knowledge that ever so often someone will say, "Bill Hughes, isn't he the guy who was involved in Abscam?" remains as something that will linger in his life.

Four businessmen who stumbled into Abscam innocently have more serious problems. They were pulled in when one of the FBI's middlemen, a convicted con man, decided to run a scam of his own on the side, taking up-front money from them with the promise of phony Arab funding for their businesses.

One has been divorced by his wife. Two say they tried suicide. All four have businesses that are now deeply in debt.

One of those who attempted suicide, Richard Stanczyk of Dillon, Colo., testified before a congressional subcommittee last month that as a result of Abscam, he has lost his wife and his Colorado tax and accounting practice. "I have incurred $212,000 in liabilities. I have lost friends. I have lost my own reputation and clients."

Not even the FBI knows how many innocent victims were hurt by the investigation that featured FBI agents posing as representatives of phony Arab sheiks. Many members of Congress whose names came up during the investigation believe their reputations may be damaged irreparably although they were never offered bribes.

The Senate is expected to organize its investigation this week. The bipartisan effort is being pushed by Sens. Alan Cranston (D-Calif.) and Ted Stevens (R-Alaska) and has widespread support. The major remaining question is whether it will be handled by an existing committee or whether a special committee should be appointed.

A House Judiciary subcommittee, headed by Rep. Don Edwards (D-Calif.), has already held extensive hearings, and plans another series beginning next Monday. The House and Senate hearings are expected to be unpleasant, not only for the FBI, but also for members of Congress who are unlikely to forget the videotaped image of a colleague stuffing money into his pockets.

For Hughes, a former prosecutor described by one colleague as "so clean he squeaks," Abscam started in November, 1979, when his wife took a phone call from a friend, a banker who said he wanted Hughes to meet a group of men interested in investing up to half a billion dollars in new construction in his district.

Joe Silvestri, an FBI middleman who claimed to be representing the group, wanted to meet Hughes, so the congressman told him to call his scheduler to set up a meeting in his office. Instead, Silvestri kept calling, dropping names, and trying to get Hughes to meet him for a drink.

"I didn't know where this guy Silvestri was coming from, but I knew something was wrong," Hughes said. "I worked 10 years as a prosecutor. I've seen all kinds. I smelled something was wrong."

Hughes, chairman of the House Judiciary subcommittee on crime, never met Silvestri. Ironically, he warned Rep. James J. Florio (D-N.J.) to stay away from Silvestri just as the con man was waiting in Florio's congressional office.

"But I am still to this day trying to explain that I've done nothing wrong," said Hughes. He asked the FBI to tell him what was going on and says the answers were "evasive."

He says he was assured by the FBI that no bribe offer was approved for him, but two weeks ago a memo initialed by FBI Director William H. Webster surfaced, indicating that a $50,000 bribe had been authorized for Hughes.

In a country where people have a constitutional right to be presumed innocent until proved guilty, Hughes believes the FBI owes him an explanation.

If they fail to provide sufficient information to indicate why he was a target, he said he may file a lawsuit.

"I think my constitutional rights were violated in a proceeding that used my name and my good reputation at the suggestion of the FBI. People have a constitutional right to be secure in knowing their government without cause will not single them out for harassment and abuse," he said.

Among the other congressmen who have been linked to Abscam are: Florio; Rep. James J. Howard (R-N.J.); House Judiciary Committee Chairman Peter W. Rodino Jr. (D-N.J.), whose son-in-law was offered $25,000 just to set up a meeting with Rodino, and Sen. Larry Pressler (R-S.D.), who was taken by Silvestri to a meeting but was not offered a bribe.

The FBI explanations so far have been sketchy. In a television interview last September, Webster said, "We're only investigating people who we have reason to believe are engaged or would like to engage in crime."

After Pressler spent two years trying to get the FBI to tell him what was going on, Webster sent him a letter March 10 saying, "There is no reason to believe you were 'engaged or would like to engage in crime.' " But the others have received no explanation.

In addition to the effects of Abscam on innocent members of Congress, Edwards said he is interested in finding out why the FBI did nothing to protect the four businessmen who ended up entangled in Abscam, even though they had committed no crimes.

They told a congressional committee last month that when they became suspicious, they were reassured by Chase Manhattan Bank, which was cooperating with the FBI. And when one of the businessmen became even more suspicious, he checked with the San Diego FBI office which assured him that there were no problems.

On March 11, the businessmen filed a $500 million lawsuit against the FBI and Chase Manhattan.