Open for lunch with Jenkins Hill menu from downstairs. Monday through Friday, 11:30 a.m. to 2:30 p.m. For dinner with Yolanda's Italian memu, daily, 6 to 11 p.m. AE, BA, D, MC, V. No reservations. Prices: At dinner, pastas $3.50 to $4.50, other main courses $4.75 to $7.50.

Now I know what lonesome means. Lonesome is being a restaurant critic and eating unpalatable food in a full restaurant. Lonesome is wondering why everyone else is there, when you have left full plates and walk out hungry. Lonesome were my dinners at Yolanda's al Campidoglio.

There was a time when eating Yolanda's pasta made me feel sorry for the rest of the world missing it, rather than for myself. That was when Yolanda was cooking at Chelsea Court,and her bargain-priced pasta was a delicious surprise. When she moved to Adriatico and cranked her magic pasta machine for that uptown neighborhood, dining with Yolanda began to have its ups and downs, its good days and bad days. Now, in a lustrous Capitol Hill setting upstairs from Jenkins Hill (which does the luch menu), in the glow of highly polished brass and skylights, I have yet to find a good day.

So why the crowds? Are brick walls and floors of Mexican tile and antique wide floorboards enough? Will hanging plants and high arched windows bring a steady stream of fans? How far will people travel and how much will they put up with for tables set with candles in hurricane lamps and outsize wooden salt shakers and peppermills? Are not bentwood and chrome and cane to be found elsewhere? And don't other Capitol Hill restaurants also serve with charming ingenuousness by youthful waiters and waitresses who appear to enjoy their jobs?

Surely it is not the price that fills the tables. Most of the pastas cost over $5, which is a cut below the top-priced Italian restaurants but not low enough to serve as a reason for climbing Yolanda's stairway. A three-course dinner with a moderate portion of wine will hover close to $15 per person.

Agreed, it is fun to watch young men under Yolanda's scrutiny rolling long sheets of yellow pasts, for the kitchen is in full view of the dining room. No, catching a few glimpses of the kitchen action does not reveal what turns all that industry into gustatory disillusion.

One would expect those homemade pastas to be the best in the house. But the fettuccine verdi con mussels, though its pale green ribbons of noodle were thin and supple and its aroma wonderfully heavy with garlic, tasted so bitter as to destroy the delicacy of the mussels and upstage even the garlic. An aberration, one might think, in view of the roomful of dinners. But then the lasagne was so limp it nearly disintegrated, and its bechamel had no more flavor than flour-water paste. A respectable tomato sauce tried bravely to save the dish. It couldn't. The same frail noodles and bechamel covered a blunt ground-meat-and-garlic stuffing to become cannelloni. Ribbons of noode, assigned the title fettuccine alfredo, sat limp in a pool of thin cream.

It is hard to ruin spaghetti alla carbonara for someone fond of bacon. And at Yolanda's the bacon was crisp and plentiful, the grated cheese savory. But again the pasta was overcooked, and this time sat in a pool of grease that stood about a quarter of an inch in the bottom of the dish.

Not that pasta is all Yolanda's kitchen ruins. A whole fish, said to be fresh rockfish, was too salty to eat, even if its mushy, strongly fishy flesh had been tempting. Veal scallops, also highly salted one day, had been pounded nearly to hamburger. As for what the menu lists as specialties, the costatelle alla milanese di maiale turned out to be a pork chop breaded and slowly sauteed so that the interior became dry and hard while the breading remained pale and soggy. Not easy to do.

All this was preceded by a salad as salty and greasy as the main dishes - a sprinkle of grated cheese helped, as did removing the brown edges from the greens.

And that was preceded by appetizers which range from oysters Rockefeller (boring, topped with little but spinach and cheese), to clams oreganata (bland and sandy), to mussels alla Yolanda (in a delicious garlicky broth with onions melting into it, but one day the mussels were so deficient in freshness that most were not open, and those that were open tasted dry).

Maybe everybody else was filling up on the warm crusty bread and clams posillipo - cherrystones briefly cooked in a robustly herbed tomato sauce, thick and rich and fresh-tasting, and well worth dunking that bread into. At $3.95, it deserves to be the star of the menu.

As modest as the food is, the wines match it, a small list of Italian wines averaging $6.50. Inglenook is the house wine. Cannole is the dessert worth trying, unless you crave commercial spumoni or pale chocolate mousse with gelatinous whipped cream.

With few exceptions that I found, however, Yolanda's al Campidoglio is a nice place to visit, but I wouldn't want to eat there.