A federal grand jury foreman here has charged his Justice Department with obstructing an investigation into charges that aides to President Carter were implicated in a scheme to fix the legal problems of fugitive financier Robert L. Vesco.

In a letter of resignation to Chief U.S. District Court Judge William B. Bryant on Tuesday, the foreman, Ralph E. Ulmer, made several general charges that appear to parallel allegations that Robert L. Herring, a convicted Georgia businessman, has made repeatedly in the past several months.

Ulmer charged that information had been withheld from the grand jury, delays arranged, a witness told to be less than candid with the FBI, and the bail system "perverted into a tool of harassment."

"The cover-up activities are being orchestrated within the Department of Justice under the concept that the administration must be protected at all costs," Ulmer wrote.

He said his resignation was a protest "against the president's reluctance to take the steps called for by the involvement of his own aides." Ulmer declined to elaborate on his charges in a phone interview yesterday, citing the grand jury secrecy rule.

A Justice Department spokesman yesterday released a copy of Ulmer's letter and an affidavit from Herring in April in which the former Georgia tractor salesman said he had talked with Ulmer on several occasions. In the affidavit. Herring made several claims of attempted interference in the Vesco case by Carter administration representatives.

Michael E. Shaheen Jr., head of the Justice Department's internal investigation unit said yesterday that his office had found Herring's accusations "to be without merit."

There was no sign yesterday that the other members of the Vesco grand jury shared Ulmer's views. Judge Bryant said in an interview he wasn't aware of the other grand jurors' feelings but that he was "curious" about Ulmer's letter of resignation as foreman.

"Things don't move fast enough for him," Bryant said. He added that he found Ulmer's two letters -- he first tried to resign July 19 -- vague.

Bryant said he wanted to talk with Ulmer again before deciding whether to grant his request to resign as foreman and member of the jury.

Justice officials said there was no rule against Ulmer's contacts with Herring, a witness, outside the grand jury.

Phillip B. Heymann, head of the department's Criminal Division, acknowledged that the Vesco investigation had been troubled by changes in attorneys and a few administrative foul-ups. But he insisted it had been "absolutely rigorous and quite exceptionally probing."

No one from the White House has contacted the department at all about the case, he said.

The investigation started last fall after columnist Jack Anderson reported that Herring and some other Georgians had agreed to approach Carter confidants Hamilton Jordan and Charles Kirbo on Vesco's behalf.

Vesco fled the country several years ago after being indicted on charges of stealing millions of dollars from a publicly held company.

Herring hired Spencer Lee, a boyhood friend of Jordan's, to talk to the White House aide about Vesco's problems. But Lee has testified he talked only with Jordan aide, Richard Harden.

Heymann said that the investigation was being transferred from the department to the U.S. attorney's office in the District of Columbia because of the barrage of charges by Herring and more recently by Ulmer.

In charging that information had been withheld from the grand jury, for instance, Ulmer appears to be referring to a package of allegations from Herring that got lost in the mail, Justice officials said.

Likewise, Ulmer's reference to the perversion of the ball system seems to be directed at Herring's complaint that his bond was set at $500,000 last fall because he threatened to expose a fix between the Carter administration and Vesco.

Columnist Anderson later acknowledged that letters he cited as evidence of wrongdoing by Jordan and Kirbo had been fabricated.

Herring has since been indicted on another charge -- that he diverted $500,000 from his Georgia company before declaring bankruptcy.

Ulmer said in the phone interview yesterday that he was particularly disturbed by a July 30 memo on grand jury procedure from Carl S. Rauh, the U.S. attorney in Washington.

It stated that while "the grand jury's wishes control," prosecutors should attempt to "screen out improper or irrelevant questions," and suggest that the grand jury vote if there is a disagreement about whether certain witnesses called.

"That doesn't seem fair," Ulmer said. "It inhibits the whole point of the grand jury, bringing the life experience of 23 citizens into the process. I can't operate under such a system."

Bryant said he had told Ulmer "that they're not to be rubber stamps for any prosecutor. So when he came in and expressed some disenchantment, I just told him that whatever you want in the way of evidence or witnesses, just tell the prosecutor you want it."

"If it's not forthcoming, you can apply to the court (the judge)," Bryant said he told Ulmer. The judge got a resignation letter, with copies sent to the press, instead.