Don’s Lunch Van, a Westbrook institution for nearly 40 years, has been shut down by the state for violating sales tax law, according to Maine Revenue Services.

The Main Street business has been parked in the same spot for more than a decade and is now inside an enclosed seating area. It closed Wednesday “until further notice for personal reasons,” according to its Facebook page.

A sign posted on the door by Maine Revenue Services says the business’ registration certificate “has been revoked for noncompliance” with state sales tax law. The agency would provide no further explanation and a spokesman for the Maine Department of Administrative and Financial Services said laws protecting personal taxpayer information prevent officials from providing specific details about the situation.

However, the statute cited on the sign says a registration certificate can be revoked for failing to pay sales taxes owed to the state. It can be reissued if delinquent taxes are paid or a court determines revocation was not warranted.

Devoted fans of the eatery, known for its cheeseburgers and lengthy list of condiments, used the business’ Facebook page to express their disappointment about its closure and their hope that it would reopen soon. Some even offered to help pay any taxes owed the state.

Janet Snow of Windham is a 68-year-old self-described Don’s Lunch “groupie.” She said she goes out of her way to stop for a cheeseburger with fried onions and red relish, two of the many choices of free condiments, every time she drives through the area.

“I tell my grandchildren, my truck automatically pulls into Don’s Lunch when I’m in Westbrook,” said Snow, who has been eating there since it opened decades ago and still goes at least once a week.

Mike Sanphy, a Westbrook city councilor and former longtime member of the Westbrook Police Department, said it’s popular with everyone from police officers to plow-truck drivers to people leaving nearby bars because it’s quicker than a sit-down restaurant, it’s open late and the food is good and cheap. A cheeseburger and onion rings is less than $5.

“It’s been a longtime downtown venue, almost a landmark, really,” Sanphy said. “If they don’t reopen, it’s going to be missed by a lot of people.”

Original owners Don and Yvonne Richards opened the business in 1976 after buying a box truck from the owner of Rapid Ray’s in Saco, who had upgraded his mobile burger joint to a newer vehicle. They modeled the business after Rapid Ray’s, including calling their double cheeseburger the Big One.

When it first opened, it was located on the west end of Main Street in the parking lot of The Muffler Shop. The food truck opened when the shop closed for the day and served burgers and fries until the early morning.

Among its customers were the late-shift workers from the S.D. Warren paper mill.

They sold the business in 2001 to Bill Bombard, who moved it to its current location on the other end of Main Street. In 2012, when Bombard decided to sell the business, Jim Richards, the son of the original owners, bought it back. At that time, it was based in a beige GMC van – its third vehicle.

Don’s Lunch opened at 11 a.m. every day but Sunday and stayed open until midnight during the week and 2 a.m. on Fridays and Saturdays.

In November, the business built an enclosed, heated seating area around the truck.

A message left on the phone line at Don’s Lunch was not returned Friday.