Since limited home rule was established for the District nearly a decade ago, Congress has not involved itself in the kind of day-to-day detail of city government operations as it once did.

But when it comes to issues near and dear to the heart of someone who also happens to be a Washington resident, it seems members of Congress sometimes just cannot resist.

This means that city officials over the last few weeks, during budget hearings before the House Appropriations subcommittee on the District of Columbia, have at times found themselves answering questions not normally on a congressional hearing agenda.

For example, why are gas pump nozzles at D.C. service stations too heavy for a congressman's wife to lift at the self-service station--and what the city plans to do about it. (Answer: It's U.S. Environmental Protection Agency's requirements that are responsible, and the city is working on it.) Why potholes aren't repaired faster. (Answer: The amount of repair work has increased from six miles a year to 40 miles annually over the past four years.)

Here are some other tidbits of information on the day-to-day functions of various D.C. agencies that have come out in the recent hearings, some in answer to questions and others volunteered in testimony:

* University of the District of Columbia President Benjamin H. Alexander gave new meaning to the phrase "food for thought" when he testified.

Alexander told the appropriations panel that grades are improving at UDC with the added incentive of "an elegant dinner" at the end of the year for students that get better than a 3.5 grade-point average on a scale of 4.0.

"Surprisingly, a number of students who had never thought in terms of working for a 3.5 now are because they want to go to that dinner next year," Alexander said.

Students that have returned after being put on probation for poor scholastic performance have improved the second time around, he added.

* Right-turn-on-red is now allowed at most intersections in the District at least some of the time, testified Thomas M. Downs while he was still head of the city's transportation department.

When right-on-red went into effect in December 1979, it was allowed at only about 18 percent of the city's intersections. The District had had a two-year dispute with federal officials over U.S. requirements allowing the turns except where prohibited with a sign. The city lost on the rule but put the prohibiting signs up at 82 percent of the intersections.

Now 35 percent of the intersections allow the turns all the time and 41 to 42 percent allow it during off-peak hours, Downs said.

* At the end of next year, no water meter in either commercial or residential buildings in the city will be more than 2 years old, William B. Johnson, director of the Department of Environmental Services, testified.

With the help of a $2.5 million supplemental appropriation last year, the department has bought all new meters and is installing them "at a rapid rate."

Johnson said this should mean a substantial improvement in water billings, which had became notorious for wild inaccuracies.

* About 80 percent of the 425 written complaints received by the Washington Metropolitan Area Transit Commission, which oversees interstate taxi service, involve trips to or from National Airport, commission executive director William H. McGilvery said.

Prosecution of drivers who overcharge should become simpler under new Federal Aviation Administration regulations that will make the matter an administrative proceeding, McGilvery said. Currently, the commission must prosecute these cases in court.

For example, one driver was taken to court on 10 or 12 complaints, McGilvery said, but the overcharges ranged from $1.12 to $10. That's a lot of trouble for a little money, he pointed out.