Fourteen members of Congress who are Vietnam-era veterans yesterday asked president Carter to expand health care, education and job benefits for their own fellow veterans to help reverse the "wrongful treatment" accorded them since the war.

Spokesmen for the group said they told the president in a meeting that the major veterans organizations and the public at large, have neglected their cause because of the war's unpopularity.

"The Vietnam veteran hasn't had a constituency," said Rep. David Bonoir (D-Mich.), "not in the traditional organizations and not on the Veterans Committee in Congress. Our purpose is to finally build one."

The group also asked for declaration of a "Vietnam-era Veterans Week" and a presidential fireside chat on the subject as a way of rehabilitating the image and recovering the self-respect for veterans who they believe were never properly welcomed home.

Bonoir said "there was some sensitivity" on Carter's part because of "his own concern about his son" who served during the Vietnam period. But Carter made no commitments, the group said.

Presidential spokesman Rex Granum said the White House's official position on improvements for Vietnam-era veterans would be the subject of a statement expected within the next few days.

Specifically, the Vietnam Veterans in Congress group is seeking:

Private sector employment incentives for Vietnam-era veterans.

More tuition benefits comparable to those made available to World War II veterans.

More money for psychological and drug abuse counseling - a particular need for those who served in Southeast Asia.

The members said they would shortly introduce a Vietnam veterans' readjustment act to put the veterans "on equal footing with those who did not serve and with veterans from other major wars."

Some of the members suggested they would support the president's controversial Civil Service revision package, which would substantially reduce veterans' perferences now used primarily by older veterans, in exchange for presidential support of their efforts.

Granum said, however, that the meeting did not involve "what you would call horsetrading."