Farmers in the east of England are reporting problems with diesel – including low fuel pressure and filters that become repeatedly blocked.

The problems appear related to an increase in the fatty acid methyl ester (FAME) content of diesel fuel, which influences its performance.

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FAME is the generic chemical term for biodiesel derived from renewable sources.

Norfolk farmer and contractor Chris Townsend said he was changing the fuel filters on his tractor every 100 hours rather than the usual 500 hours.

“Something is blocking the filters and we are getting error codes telling us that the fuel pressure is low,” said Mr Townsend, who farms near Diss.

“As soon as the fuel pressure drops, it shuts the power down and stops you using it.”

Spare filters

Mr Townsend said the problem had become so frequent he was now driving around with spare fuel filters in the tractor cab so he could replace them more quickly.

The fuel was the problem rather than the tractor, he suggested, because his combine harvester had also been affected throughout the summer.

“We do all the servicing ourselves and the combine had a brand new set of filters. We did 90 hours of combining and hit the same thing.”

In a letter to Mr Townsend, fuel supplier Certas Energy said test results of fuel samples from a number of customers showed that all fuel was on specification.

“Certas Energy have taken this issue very seriously and have investigated our supply chain to understand if any issues have been caused,” the company said.

“We have received certificates of quality from our suppliers that also confirms all fuel delivered into Certas Energy tanks was on spec and to government standards.

Fuel quality

“To conclude our findings, fuel quality has not been found to be the issue.”

The letter confirms that the FAME content of fuel increased from 5% to 7% in January 2019 – and is due to rise to 8.5% in 2020.

“The increased FAME content is found to act as a cleaning agent within tanks and thus creating the recent issues experienced with filters,” said the letter.

There was also an increased risk of bugs and water retention along with a greater chance of fuel issues during winter, including waxing at low temperatures, it added.

The letter said alternative FAME-free fuels were available.

Norfolk-based AF buying group said it too was aware that some of its members were reporting issues around fuel quality and fuel filter life.

“As a matter of urgency, we are establishing what the issues are from a scientific point of view,” it said in its newsletter to members.

“We are in communication with the fuel companies and independent laboratories.”