A Baltimore federal grand jury is investigating allegations that a prominent Washington businessman and his partner in a construction firm evaded federal income taxes by failing to report work done on their homes by their company, according to sources.

According to the sources, John W. Lyon and Larry A. Campbell, who own Excavation Construction Inc., one of the area's major construction firms, are alleged to have received work worth thousands of dollars that they failed to report as income.

Lyon, the president of the company, is also president of Parking Management Inc. and a member of the board of directors of the National Bank of Washington. Campbell is general manager of Excavation Construction, the flagship in a network of some 30 area construction firms.

Evidence introduced in an earlier trial that grew out of the wide-ranging grand jury investigation indicated that company records having to do with work done at one of the owners' houses had been altered.

Neither Lyon nor Campbell could be reached for comment yesterday, although Lyon sent word through a secretary that "he is not interested in talking to the press or having any of his representatives talk to you."

Jacob Stein, an attorney who has represented Lyon in responding to requests by the U.S. Attorney's Office in Baltimore, said that he has no access to grand jury testimony. "You have more information than I have heard," he said.

The income tax investigation is the latest direction taken by the Baltimore grand jury, whose investigation is one of several law enforcement probes of Bladensburg-based Exacavation Construction in the past two years. In September the company filed for reorganization under federal bankruptcy law, blaming both cash flow problems and a cloud of suspicion created by the continuing investigations. An auction of some of the firm's assets is scheduled for mid-December.

Three convictions of corporate officials related to Excavation Construction have grown out of the law enforcement investigations this year. Last week, corporate secretary Robert P. Jenkins was convicted of lying to a Washington grand jury that is investigating bribery and corruption allegations against former D.C. Superior Court Judge Robert H. Campbell.

Earlier this year, two men who headed a firm that purported to be a minority-owned and operated small business were convicted of fronting for Lyon and Campbell to obtain federal contracts.

In still another investigation, the Maryland State Police are said to be probing whether the former commander of a state police unit assigned to guard the governor illegally used state equipment to check for bugging devices in Campbell's home and offices.

According to sources, the allegations involve Norval Cooper, who headed the state's executive protection service during the tenure of former governor Marvin Mandel. Cooper retired in July. Sources said that state police equipment had been used to conduct numerous debugging sweeps of Campbell's house and offices. Such activities are not normal police operations.

In another development affecting the multimillion-dollar heavy construction firm, the state of West Virginia fired two state highway inspectorsors last week for reportedly accepting a fishing trip to Bimini from a company official while the company was at work on a $36 million state road project.

Highway department spokesman Gary Chernenko said that the employes, James E. Blackburn and Paul Perry, accepted a flight to the Bahamas and four-day fishing weekend on the company's boat, the E-C Rider, in June 1977. although the two men had been inspectors on an Excavation Construction project which involved improving some 14 miles of the West Virginia turnpike, they were not working as insepectors on the project at the time of the trip, he said.

Chernenko said the investigation turned up no evidence that the two men had done favors for Excavation Construction in return for the trip but that the trip violated departmental and state policy. The trip was arranged by Tom Tucker, who supervised Excavation Construction's West Virginia jobs.