Dhakuria: Petrol allegedly diluted with water and dispensed from an Indian Oil pump near the company's regional office caused a month-old Maruti Suzuki Swift to sputter and stop every few metres before two trips to a workshop got the car up and running.

The job card and invoice from Dewar's Garage on British India Street mentions "fuel water mix-up", based on which Sumantika Choudhury has filed a complaint with Lake police station against Uma Service Station on Gariahat Road.

An official of the Indian Oil Corporation said rainwater seepage into the underground tank of the fuel pump caused the problem. "We are upgrading the oil dispensers at Uma Service Station and water must have seeped into the tank during the process," he told Metro.

According to the official, the owner of the Swift was compensated for the damage with a full tank of fuel and reimbursement of the cost of repairing the car.

Sumantika had brought home the red Maruti Swift ZXi, the top petrol variant, from the Dewar's showroom on July 6. She visited Uma Service Station on August 6 to top off the car tank before driving to her office in central Calcutta.

"The engine started giving me trouble when I was on Gurusaday Road. The car started vibrating and the RPM needle was oscillating wildly. The engine sputtered and stopped several times and the malfunction light on the dashboard display continued blinking. I somehow drove till the Dewar's workshop," Sumantika recounted.

Mechanics traced the problem to water in the engine block of the Swift's 1.2-litre assembly. "The first cylinder of the four-cylinder engine was not getting the required power because of this," an official said.

After removing the water, the workshop returned the car to its owner the same evening with the advice that she should call immediately if the engine sputtered again.

On the morning of August 7, the problem resurfaced and Sumantika took her Swift back to the garage. By afternoon, the service manager called her to say that the fuel tank had water in it. The tank was drained out and a sample of the contaminated petrol provided to the car owner along with the job card mentioning the cause of the engine malfunction.

Metro visited Uma Service Station on Wednesday morning and found the space around the oil dispensers dug up and barricaded. A notice pasted on one of the dispensers said: "Dispensing pump replacement work in progress."

The row of cars waiting for a fuel refill was being serviced through a single dispenser.

"We are upgrading the dispensers in all fuel pumps in Calcutta. We have completed the work in most of our pumps. Uma Service Station is among the last ones where the upgrade is currently happening," said Naresh Kumar Agarwal, senior manager (retail sales) at Indian Oil.

According to a service manager at Dewar's, "water contamination of fuel" is a common problem during the monsoon. "We get seven to eight such cases every season," he said. "Water might cause the car to malfunction till it settles at the bottom of the tank because it is heavier than petrol, But water doesn't harm the car as such."

The officer-in-charge of Lake police station said the complaint lodged by Sumantika was being investigated.