The administration is making a late effort to salvage its standby gasoline rationing plan which is considered in trouble in both the House and Senate.

Both bodies must approve the plan by the end of next week or it will die. The Senate Energy Committee approved it, 9 to 8. The House Commerce Committee rejected it by a 21-to-21 tie and then sent it to the House without recommendation.

Under the Energy Policy and Conservation Act of 1975, Congress must approve any standby gasoline rationing plan within 60 days after the president submits it to Capitol Hill.

The plan is in trouble because most lawmakers dislike the idea of rationing and in particular because of the formula proposed for administering it. It would hand out gas coupons on the formula proposed for administering it. It would hand out gas coupons on the basis of one for each car. A rich person with a barn full of antique cars might get a dozen coupons while a poor person with one car would get one. And it made no distinction between people in cities who could switch to buses or bicycles and those in large rural states who must drive long distances to work. It started off with opposition from liberals and big Western states.

The administration pushed the plan through the Senate committee with a written promise to give more gas to the big rural states, up to 10 percent more than the others. Some senators are demanding that the bonus for big states be increased to 20 percent or more.

To pick up liberal support, the administration has discussed with House and Senate sponsors a provision limiting the number of cars in one family that could qualify for coupons to about three. Rep. John Dingell (D-Mich.), chief sponsor of the plan in the House, said he would prefer to change the formula to give coupons to car owners rather than to cars.

Administration officials met separately with House and Senate supporters yesterday to seek agreement on amendments that would help get the plan through Congress. Dingell said no final decisions were made. The Senate tentatively has scheduled a vote on the plan Tuesday. The House plans to vote later.

If Congress approves the standby plan, the president would have to clear with Congress again any decision to put it into effect.

Dingell said yesterday that failure by Congress to put the rationing machinery in place would be to invite a "howling disaster . . . The only thing worse than a rationing plan would be to have no rationing plan ready if an emergency hits us."

In a related development yesterday, the American Petroleum Institute reported that the nation's gasoline inventories declined 238,000 barrels a day during the week ending April 27, leaving 6.7 million barrels in stocks. This is less than oil industry executives and the Energy Department say is necessary to allow for summer driving without shortages.