Common Cause said yesterday the Senate process of confirming presidential nominees is a "rubberstamp machine" that needs a comprehensive overhaul.

The lobbying organizations, which has advocated reform of the process since 1973, recommended that nominees be required to complete full and detailed questionnaires on their personal, financial and political background.

It also recommended that the Senate set up an office on nominations to make an independent background study of the prespective appointees, including FBI checks. Such an office has been proposed by Sens. Abraham A. Ribicoff (D-Conn.), Charles H. Percy (R-Ill.) and Jacob K. Javits (R-N.Y.).

Common Cause said the Senate has traditionally based its confirmation judgement on a "negative standard - is the nominee clearly disqualified to serve?" - when it ought to "make a finding that the nominees are affirmatively qualified to serve."

It also suggested that since "time is essential element in a deliberative confirmation process," the senators should allow enough time for proper scrutiny of the nominees' backgrounds.

Common Cause said the recent confirmation of Energy Secretary James R. Schlesinger Jr. took the Senate only six house and 50 minutes.

"This short process for the secretary of a major new department makes a mockery of the system," said Common Cause President David Cohen in releasing a 150-page study of the confirmation process of 50 of President Carter's most important appointments.

Senate committees should prepare written, substantive reports on nominees they approve and explain why the approval was given, the report said.

It suggested that senators' votes be recorded in committee and on the floor for all nominees to policy-making positions.

"The prime failing of the present process' is "the task of a systematic approach," the study found. The committees have "a hodge-podge of procedures and practices for dealing with nominations. While most of the committees havesome useful practices, none do a thorough job."

Cohen referred to former Budget Director Bert Lance, who was confirmed in January after only cursory hearings and investigation and who resigned Sept. 21 after disclosures about his banking backgrounds.

"The Lance controversy in part resulted from a confirmation process that is haphazard and leads to senators acting and voting out of ignorance," Cohen said. "If it had not been Bert Lance and the Committee on Governmental Affairs, it would have been another nominee.

"If the Senate is not willing to learn the lesson of the Lance affair by improving its confirmation process, then we are sure to face the same kind of problems in the future."

The Common Cause study found that: In 18 cases the committee approved the nominee on the day of the nomination hearing.

Only 10 hearings went beyond a single day; only two exceeded two days.

In only six cases did committees prepare substantive reports explaining their recommendations.

Printed hearing records were available to senators before the votes in only six cases.

Committee votes of individual senators were recorded in only half the cases.

Recorded Senate floor votes were taken on only six nominations.

In only 17 cases were nominees required to make public a statement of political activities and recent contributions to political candidates.

Financial disclosure statements were made public by committees in only 14 cases.