WEST PALM BEACH, Fla. -- West Palm Beach says the number of police cars with engine problems has now increased to 36, as the investigation into the cause is still underway .
Two other agencies, Miami-Dade and Miami Gardens, also report police cars with similar issues.
West Palm City Administrator Jeff Green said mechanics have found diesel fuel in gas supply tanks that were meant to be fueled with unleaded.
Miami-Dade has sidelined around 50 of their cars, reporting the same issue, 35 of which definitely will need a new engine.
How diesel ended up in their tanks remains the big question, but city officials think they have narrowed it down.
“We believe at this point that it was related to the fuel supplier," Green said.
West Palm Beach uses Mansfield as a supplier. Miami-Dade uses Indigo. Neither companies responded to WPTV's questions on Wednesday.
At the same time Ford is still investigating on their end, checking several of the West Palm engines the automaker took back to Detroit for a closer look.
The problems started last week when two cars suddenly had engine failure.
“They went down hard," West Palm Beach City Fleet Manager Mario Guzman said. "They just stopped working.”
The symptoms were quiet. No check engine light came on.
All cars with issues have the same Ford Interceptor motor and are less than three years old.
“If you opened them up they looked like they had 300,000 miles," Guzman said.
Guzman said because the Interceptors are high-performance engines, they seem to have been more susceptible than other cars in the fleet.
Green said the city has switched to a different fuel supplier until they have a better idea of what went wrong.
Six engines have already been replaced, but to replace all the engines is going to be costly. Green said he's expecting the city to have to pay around $200,000.
If the city can confirm the fuel supplier is at fault, Green said they're going to go after the supplier to get their money back and make sure the taxpayer is not on the hook for the cost.