Washington Diplomat majority owners Jimmy Hill and his son, Duncan, are being sued by a Detroit businessman, and the Pontiac Silverdome, where Hill's team played before moving here, also may file suit.

The Diplomat franchise, formerly known as the Detroit Express, moved here in February, and, according to General Manager Duncan Hill, is already "in a desperate situation."

"We are fighting as hard as we can to come up with a package now, with or without our long-term involvement," Hill said yesterday. "We're flying to New York (today) in hopes of coming up with such a package."

North American Soccer League sources say the Diplomat franchise could fold at the end of the season unless the Hills can find a buyer, or come up with a major investor. Madison Square Garden Corp. disbanded the team last fall after running it for two years and averaging almost 20,000 fans a game last year.

"It is highly likely there will be a franchise here next season," Hill said. "But that will be heavily dependent on what happens in the next two weeks."

The team is averaging only 12,298 in 15 RFK Stadium dates this season. But more than one-third of the total gate (184,475) came in two home games with the defending champion Cosmos.

In developments this week, a Pontiac, Mich., city attorney, Al Strom, said the Hills' franchise owes the Pontiac Stadium Authority $150,000, and it may file suit to collect soon. The attorney said a payment of $80,000 -- said to be part of a settlement figure negotiated between the team and the stadium to break the lease -- was due in May but has not been paid.

The other $70,000 the city says it is owed was to have come from two exhibition games, to be played this summer, in the Silverdome. Chicago officially canceled the first game. A second, with Detroit's new ASL team, has yet to be scheduled, according to a Diplomat employe.

Duncan Hill, who runs the club on a daily basis, said yesterday: "We do owe the Pontiac Silverdome money. We agreed to pay them because we moved out and left the city without a soccer team. But now they have another team, with the same name. They have revenue from the new team, but they still want our money.

"We've talked with the stadium authority once and acknowledged that we do owe them the money, and wouldn't be able to pay them for a couple of months because the crowd flow here in Washington wasn't as good as we expected. But we also have $100,000 worth of boards and AstroTurf from the indoor season that they're holding in the stadium. It was suggested that we make a tradeoff, but I haven't heard a word from them yet.

"Also, the Silverdome charged us outrageous rent rates, then charged the new team 300 percent less than they charged us. It wasn't fair."

Sonny Van Arnum, an original partner in the Hills' franchise and current owner of the Detroit Express ASL franchise, dropped one suit against the Hills for a cash settlement and the right to use the name "Express." "We owe Van Arnum money, but not until 1982," Hill said.

Roger Faulkner, another original partner, was fired as an assistant general manager and said he has been paid for less than six months of the 24 months left on his contract. Faulkner said the Hills filed a countersuit in an Oakland County, Mich. court, one week after he filed in mid-December.

"I have filed suit for $100,000," Faulkner said yesterday from Bloomfield, Mich. "I just hope they have enough money for me to collect."

Responded Hill: "Faulkner owns one-half of 1 percent and we fired him. If he didn't slander the franchise, we would pay him the remaining months -- I think it's 24 -- of his contract. But he slandered the club and tried to find three or four people to take over the majority interest of the team. We felt he broke his agreement, so we weren't going to continue to pay anyone who tried to undermine us."

Several sources have said that Trevor Francis, the team's best player when it was in Detroit, has not been paid the full amount of his contract and is considering a suit. Francis is said to be playing soccer in Europe now, and could not be reached for comment last night.

"It has been reported that we owe Francis money for 1978 and 1979, when I was in Saudi Arabia," Hill said. "But we had a three-year contract and the player didn't return (to Detroit) for the third year. He was supposed to make all sorts of promotional appearances and didn't. We just paid his federal taxes in Detroit, two months ago -- about $13,000. As far as I know, there is no lawsuit concerning Francis."

There were also several Express staff members who said they were promised severance pay by the Hills when the franchise moved, but have not yet been paid.

"As far as I know, we don't owe anybody in Detroit any money, other than the Silverdome," Hill said. "Jimmy and I raised $500,000 to pay off the bills there, much of it our own money. I signed some of the checks to pay people."

The Hills have been seeking investors in Washington the last four months, Hill said. Gary Lemmen, who still lives in Detroit and owns 28 percent of the team, said the current ownership would be willing to sell the franchise "if the money was right." The Hills have put about $1.5 million of their own money into the franchise.

Hill, who wanted to run a tight budget this year, felt compelled to sign Johan Cruyff for $175,000 for the final half of the season in hopes of boosting attendance. But Cruyff has played one complete game since July 1 and may not play any more this year because of a groin injury.

To help pay for Cruyff, who was hurt before he even arrived, the club sold Peter Baralic, generally acknowledged as one of its top three or four players, to Tulsa, for between $40,000 and $80,000. But Baralic refused to report to his new team and the Dips received no money.

"What we have on our hands is an injury-prone superstar (Cruyff) who doesn't play much," Hill said. When asked if he thought Cruyff would play this season, Hill replied, "I've given up hope."