IF AMERICAN OIL consumption were to rise only by the modest increment of 3 percent, oil imports would exceed the absolute limit that President Carter has set. To overstep that limit would constitute an immensely damaging confession of failure, for both the president and the country. But the administration has not yet worked out a clear and convincing strategy to enforce it.

The choices are not attractive, and they invite procrastination because the trend in oil consumption is, temporarily, slightly downward. Gasoline sales have fallen because prices have risen. In the months ahead the recession seems very likely to hold down demand for most fuels. The dangerous passage will come after the economic recovery begins.

Several weeks ago we raised in this space the question whether American oil imports this fall will rise above 8.2 million barrels a day, the president's limit for 1979. The answer from the administration is that there's no chance of it. The White House considers the limit to be a year-long average, with last spring's shortfall offsetting higher imports in the months ahead. To put it coarsely, the 1979 limit was a purely rhetorical device. But the figure for the years ahead is an altogether different matter. "Beginning this moment," Mr. Carter said in July, "this nation will never use more foreign oil than we did in 1977 -- never." That was 8.6 million barrels a day. Last month imports -- just under half of the country's total oil supply -- were running about 8.1 million barrels a day. It wouldn't take much of a lift in the economy to send imports crashing up through that ceiling.

The administration is considering a variety of mechanisms to prevent it. One possibility would be some variation on the import quotas that prevailed before 1973.Another would be allocations, of which the country got a taste during the gasoline shortages last spring. Still another would be tariffs. There are better strategies than any of these -- accelerated decontrol of crude oil, immediate decontrol of gasoline prices, sharply increased gasoline taxes -- but unfortunately the White House does not seem to be thinking about them at all. It makes sense to constrain gasoline use more forcefully than industrial fuels and heating oil, on which jobs and winter warmth depend.

President Carter was right to commit the country to hold future imports down to a specific number. That pledge tells the rest of the world that the United States does not intend to preempt steadily large shares of the world's oil, driving prices higher and higher. But to be credible, that pledge has to be backed by realistic means of enforcing it. Enforcement is always an uncomfortable subject. But it is certainly not going to get any easier to handle in a presidential election year, when oil imports may begin inching upward toward Mr. Carter's now-and-forever limit.