While the committee rewriting the Senate's code of ethics yesterday tentatively adopted a 15 per cent limit on outside earned income, the same provision was facing some difficulty in the House Rules Committee.

A key amendment offered by Sen. John Chafee (R-R.I.) would have limited senators to $15,000 a year in outside earned income. It was defeated 9 to 6 by the Senate ethics committee.

Under the 29 per cent pay increase, which went into effect Sunday, senators and representatives earn $57,500 a year, as opposed to the $44,600 they earned before. Under the 15 per cent limit on outside earned income they could earn an additional $8,625.

Chafee said he was "bothered by the whole philosophy of the limit." He was joined by Sen. Daniel K. Inouye (D-Hawaii), the only Democrat to join ctmmittee Republicans in voting for Chafee's amendment. "You're going to ask the most severe, open, naked disclosure law in the world. That should suffice," Inouye said.

Honoraria for speechmaking is also included in the limit, and Inouye added, "By this bill speechmaking is dirty. I resent that."

The Senate committee did agree by a 11-to-3 vote to increase the proposed limit on the amount that could be received for a single speech from $750 to $1,000. Sen. Jacob K. Javits (R-N.Y.), who offered the amendment, said, "for our own dignity we should increase" in amount above what the House ecevies. The proposed House code has a $750 per speech limit.

The Senate's current ethics ctde has no limit on outside ceiling on htnoraria.

Meanwhile, despite leadership pressure to help the House code clear the House Rules Committee, opposition to the earned-income limit left some doubt about the outcome in Rules.

House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) met with the Democratic members of the Rules Committee for breakfast yesterday. According to one source, he told them his reputation was on the line and urged their support.

But Rep. Morgan F. Murphy (D-Ill.), one of those opposed to the income limit, said, "He was firm, but so were we."

In the Rules Committee, which is expected to vote on the matter today, the issue is being framed as to whether the code should be completely open to amendment on the House floor or whether the vote should be limited to up and down votes on various sections, but not allow amendments changing the details.

O'Neill and Rep. David R. Obey (D-Wis.), whose commission drafted the proposed code, favor limiting the amendments. O'Neill would only say yesterday, "I think we'll get a rule that will satisfy everybody," though he predicted the 15 per cent limit would pass "overwhelmingly" on the floor.

Obey contended before the Rules Committee that, given the chance, members would tear the package apart with amendments that would make it so restrictive that it would be unworkable and ultimately voted down.

But Rep. John B. Anderson (R-Ill.) said members were not like mischievous schoolboys writing graffiti: on the Ten Commandments," and added, "I doubt the members would set out to destroy legislation with meaningless jargon."

Obey said if the rule were opened up on the floor he would withdrawn his proposal.

While outside earned income would be limited, unearned income from stocks and bonds, and so forth, would not, leading many members to charge it was discriminatory. Other less controversial parts of the code require fuller financial disclosure, ending of lame-duck travel, ending of slush funds for office accounts, tightening the use of the postal frank and prohibiting gifts worth more than $100 to members.