House Majority Leader Jim Wright (D-Tex.) split yesterday with Speaker Thomas P. O'Neill Jr. (D-Mass.) and the liberal wing of his party by joining the No. 2 House Republican and a conservative Democrat in sponsoring a bill calling for a balanced federal budget.

O'Neill has opposed a balanced-budget requirement on grounds that it might jeopardize social programs and would keep the government from responding flexibly to changes in the economy. He has devoted considerable time and effort in the last couple of years to heading off such an issue in the House.

But yesterday Wright called a news conference where, flanked by Rep. Phil Gramm (D-Tex.), a member of the Conservative Democratic Forum, which muscled him onto the House Budget Committee this year, and Republican Whip Trent Lott (Miss.), to announce their sponsorship of a bill designed to force enactment of a balanced budget.O'Neill later said he had no advance knowledge of what Wright was up to and would not discuss it.

This was the third time in recent weeks Wright has zig-zagged out front doing his own thing. First he organized an early letter signed by O'Neill and the rest of the House Democratic leaders urging President Reagan not to cut the synthetic fuel subsidy program that Wright helped guide through Congress last year.

This offended some liberals, who said the synfuel program was not the first the Democratic Party should move to protect.

The Wright seemed to reverse field, putting out a letter to House Democrats giving advice on how to handle questions back home on the Reagan budget cuts.

He talked of cooperation with the president, which is what O'Neill preaches constantly, but there was also a message, which made headlines, that Democrats should defend programs that help the poor. Then yesterday he was on stage with Gramm and Lott.

"I do a lot of things on my own," Wright told reporters when asked how his balanced budget bill squared with the position of O'Neill, who is the party's leader in the House.

Wright said he was speaking for himself only and for no one else in the leadership. He said he felt it was the responsibility of leaders to work not only within one's party, but also to try to work with the opposition party seeking ways to solve problems.

The Wright-Lott-Gramm plan would require the president to submit and Congress to enact a balanced budget starting two years from now. It would not apply in time of war and would contain an escape clause permitting Congress to carve out specific exemptions.

But it could be an effective check on deficit spending, Wright said, by shifting the burden of proof from those who want to balance the budget to those who prefer continued high spending on social programs.

Asked about the chances of his bill passing, Wright said he didn't know, but believes it is an idea "that should be floated to see what support we get."

The bill goes to the House Rules Committee, whose chairman, Rep. Richard Bolling (D-Mo.), agreed with Wright's assessment that he was "not wholly enthused" by the idea.

Wright was elected majority leader in December 1976, by a one-vote margin on the third ballot over liberal Phillip Burton (D-Calif.). Bolling was also a contender for the post then, and Wright won partly because Bolling and Burton split the liberals. If tradition holds, and he wins reelection, the Texan is likely to become House Speaker when O'Neill retires.