Another Senate test vote yesterday showed administration forces still unable to kill off a proposal to lift price controls from natural gas.

Asked if the 50-to-44 vote against tabling a deregulation plan means the administration cannot win on this issue in the Senate, Sen. Henry M. Jackson (D-Wash.), floor manager of President Carter's bill, said: "I don't think we can."

Jackson has fought for two weeks to end a filibuster alternately waged by both sides, but has said all along that the most important thing is to move a bill into a House-Senate conference committee, where the final version will be written. The House approved Carter's plan to continue controls, though at a higher price than now, and a majority of conferees from both houses wil probably favor his position.

Yesterday's true vote was 49 to 45 because Sen. James Abourezk (D-D.D.), a leading opponent of deregulation, switched to the other side at the last minute for possible parliamentary advantage.

The administration picked up two votes - Sen. Gary W. Hart (D-Colo.) and John J. Sparkman (D-Ala.) - from las week's 52-to-46 vote against tabling. And Sen. Dennis Deconcini (D-Ariz.) waited until the last minute to vote for deregulation, suggesting that he would have gone with the administration if it had made a difference.

If so, that means that if the administration could switch one more vote it would make a tie, which Vice President Mondale could break in favor of regulation.

But the administration from Carter on down has been working for at least two weeks trying to pick up those last votes and has been unable to do so.

Majority Leader Robert C. Byrd (D-W.Va.) again spent most of the day in a futile effort to get Sen. Russell B. Long (D La.), a leader among those who favor deregulation. Abourezk and others on the pro-regulation side to bring the gas issue to a decisive vote. Both Abourezk and Long have been using the more than 300 amendments that could be called up for votes as ammunition to tie up the Senate. Abourezk wants to avoid an up-or-down vote on deregulation; Long won't let the Senate move to a vote unless Abourezk agrees to abide by the result.

Sen. William L. Scott (R-Va.) urged Byrd yesterday to admit he can't pass the President's gas bill and pull it off the floor. Byrd refused. He has made a commitment to do everything possible to pass a bill. He ordered a Saturday session to get rid of some more amendments, which is the only thing standing in the way of final votes.

Jackson's compromise bill to continue regulation at a price higher than the President wants almost sneaked through on a voice vote when only a handful of senators were on the floor. Byrd ordered the action wiped out and all agreed they didn't want to win or lose that way.

The natural gas issue is this:

Gas, which has quadrupled in price in four years, is unregulated if conumed in states where produced, and controlled at a ceiling of $1.46 per thousand cubic feet (mef) when piped across state lines.

Carter would wipe out the distorted dual market by extending controls to intrastate gas and raising the price ceiling for newly discovered gas to $1.75 per mef. He contends deregulation would cost consumers $10 billion a year. In an effort to get regulation through the Senate, Jackson proposed raising the cap to $2.03 and making a large amount of "old" gas eligible for the higher "new" gas ceiling.

Deregulation forces, contending this is the only way to provide signigficant increased production, have amended their plan to continue controls for two years at a ceiling of about $2.48 per mef.

The Senate also passed last night a debt ceiling bill that the dilibusterers had earlier threatened to hold as a kind of hostage in the fight over gas.

The Treasury needs passage of the debt bill so it can continue borrowing next week and the government can keep paying its bills. The House has passed a different version and there will be a conference Monday, but that is time enough, fiscal experts say.