The Capital Children's Museum, suffering from a cash crunch, failed to meet its payroll last Friday, and five senior employes went without paychecks totaling about $5,000 for the previous two-week period. They have not been paid yet.

The museum's 60 other employes, half of them full time, were paid only after museum officials convinced a tenant in their building to pay the May rent early.

"Things are tough," said museum founder and director Ann Lewin. "We don't have any money in the bank."

Lewin, founder of the nonprofit, play-oriented learning facility at 800 3rd St. NE just north of Union Station, added: "I don't know how long people will continue to work if we don't get some money in here."

Lewin has raised more than $15 million for the museum since it opened in 1979, but yesterday she said her estimates show that government grants to the museum are down $167,000 from last year, corporate contributions down $119,000, private foundation grants down $149,000 and individual contributions down $30,000.

Last year's museum budget was $1.84 million, $190,000 of that from admission at $1.50 a person. This year, the admission fee has been raised to $2, which is expected to generate $373,000 in income. This year's projected budget is $1.4 million.

The $20 million fund-raising drive launched last year by Wolf Trap to replace its burned Filene Center and create a large endowment has been "a real problem," Lewin said. "As much as we all love Wolf Trap . . . a lot of people who gave to us in the past have said, 'We can't because we had to give to Wolf Trap this year.' "

Wolf Trap spokesman Jeane Young said, "We're sorry that the Children's Museum feels that way, but in our experience it is not the case. Many arts organizations have assured us that Wolf Trap is not infringing on their money raising efforts. Unfortunately, as we know, all arts organizations throughout the country are feeling the effects of the economy."

Lewin said the nationwide economic crunch has hurt. General Mills gave $1,500 to the museum last year, she said, but, "When we went back this year they said, 'No, we're giving away food this year, not money.' They had people on bread lines and soup lines where their corporate headquarters is located."

A spokesman for General Mills in Minneapolis said, "There's been a big squeeze for those who receive funds from us . . . The selection process is much more strenuous." At the same time, he said, "We have been more aggressive in providing product for free food distribution around the country."

Lewin said corporate contributions have dropped even though the museum has 150 corporate sponsors. Many are decreasing their contributions to put more money into their own communities, she said.

"Part of our difficulty is being a new institution in a city where there are a lot of museums," Lewin said. "As a brand new institution we have not uncovered our sugar daddy. We're waiting to give the name of this institution to someone who will put a $10 million endowment on it. That's not a lot of money. Paul Mellon put $100 million into the East Wing" of the National Gallery of Art.

Lewin said the museum will receive no funds this year from the National Science Foundation, the U.S. Department of Education and ACTION--government agencies that gave money last year--because "programs were abolished" or redefined. The museum is still receiving funds from the National Endowments for the Arts and Humanities and the Institute of Museum Services, she said.

Lewin is counting on a May 7 fund-raiser--a "Breakfast with Champions" at which children can meet local sports figures--to bring in some money quickly. In addition, rents from other tenants are due May 1. Meanwhile, Lewin said, "We hope that our other checks don't bounce because we expected some contributions in last week that didn't come."

The museum, which has an estimated 700 visitors a day, emphasizes exhibits in which children can learn by participating in various activities--making tortillas and "yarn paintings," running computers and printing presses, caring for a live goat, and so on.

Its 150,000 square-foot complex of buildings was purchased with a $1.7 million federal grant in 1978, and the museum was able to raise $281,000 last year by renting out 45,000 square feet of space it could not use itself.