The great fax attack of 1989 - an all-out lobbying campaign against a bill banning unsolicited facsimile advertising - backfired when the governor's fax machine was jammed for hours with unwanted messages.

Starting Thursday and continuing Friday, Gov. William A. O'Neill's fax machine has been beeping constantly, spitting out unwanted messages from angry businesses that advertise by fax.The businesses oppose a bill now awaiting O'Neill's signature that would prohibit them from marketing their products by fax without first obtaining the permission of the recipient. Violators would face a $200 fine.

Starting Thursday morning, dozens of Connecticut businesses faxed to O'Neill's office a form letter arguing against the fax ban. The letter argued it would cost the average company $6,000 a year to obtain permission before sending fax messages.

The stream of fax messages was so constant - 40 came in before 10 a.m. - that the governor's office turned off the fax machine Thursday. When they turned it back on Friday, the messages still were pouring in.

O'Neill's press secretary, Jon L. Sandberg, said the governor still hasn't decided whether he will sign the bill.

But aides to the governor said the persistent lobbying campaign proved how annoying unwanted messages can be. The inconvenience was compounded because the governor's office was unable to use its fax machine to receive information about spring flooding around the state.

"You could not have done a better job of bringing home the problem adressed in the bill that you oppose," O'Neill aide Charles Monagan wrote Thursday in a letter to the National Fax Users Committee.

Monagan urged the California-based committee, which apparently organized the fax attack, to come up with "a different and more effective way of getting your message across."

The committee doesn't have a listed telephone number, so Monagan did the logical thing. He faxed the letter to the committee's fax line.

A fax message sent by The Associated Press to the National Fax Users Committee to a telephone number listed on the committee's documents went unanswered Friday.