The D.C. City Council sidetracked an economic boycott bill yesterday after being warned that its passage voting representation in Congress for would endanger Senate approval of the nation's capital.

The council's now-delayed legislation would have required city employes to boycott meetings and conventions held in the 15 states that have not ratified the pending Equal Rights Amendment to the Constitution. It also calls on city agencies to shun purchases from North Carolina firms until all the Wilmington 10 are freed.

In a letter to all council members, the D.C. League of Women Voters warned that passage of the bill might lose votes in the Senate for the constitutional amendment that would give Washington voting representation in the Senate and House. A Senate vote is expected late next month.

"The boyctts would be directed at the constituents of 16 of the senators who are considered 'undecided' (on D.C. voting rights) and on whose votes the success of the campaign depends," league president Ellyn Swanson said in the letter.

The boycott measure was set aside on procedural grounds. Arrington Dixon (D-Ward 4) moved that the bill be sent back to the council's government operations committee, which he heads, to be revised.

Marion Barry (D-At Large), chief sponsor of the ERA part of the boycott bill, reluctantly agreed. "I'm watching to see what these senators from those 15 states do" about supporting the District's voting rights, he said.

The Wilmington 10 were civil rights activists convicted in the firebombing of a vacant grocery store during a racial disturbance in that coastal city in 1971. Earlier this year, North Carolna's governor shortened the sentences of nine still held in prison, but refuesed to pardon them.

Also at yesterday's meeting, the council failed twice to pass a resolution declaring June 11 to 17 as Gay Pride Week in the city.

John A. Wilson (D-Ward 2), sponsor of the resolution, was blocked from calling it up on procedural objections raised by Douglas E. Moore (D-At Large) and Wilhelmina J. Rolark (D-Ward 8).

Later the council rejected, by a tie vote of 6 to 6, another effort by Wilson to have the council declare an emergency to pass the same resolution.