a curious case of sticky fuel
River Canal Rescue reports there’s been an uncharacteristic peak in fuel-related component breakdowns not linked to diesel bug. It cites two identical jobs where fuel injectors were diagnosed as needing an overhaul, yet their replacements stopped working within a week, and injection pumps were found to have failed even though the diesel was clear and bright.
Upon further investigation, RCR engineers found in both cases the injector pump racks had seized solid and the nozzles were blocked, and when replacing the plunger filter head, they found the fuel had a sticky, syrup-like substance. Alongside stuck injection pump racks, injectors and filter head plunger failures, RCR is seeing cases of fuel filters blocking with wax inside them.
Managing director, Stephanie Horton, explains: “Over the last nine months we’ve come across higher than normal call-outs for injector, injection pump and fuel problems not related to diesel bug. Our contractors are also reporting reoccurring issues with these systems and ‘sticky fuel’.
“It’s definitely a type of contamination, but not one we’ve seen before. Samples have been taken and we’re trying to build a picture of the problem. Our engineers are reporting problems across the UK and this particular issue is only becoming clear when a fault reoccurs, because the diesel on the whole, looks bright and clear.
“Initially we suspected sugar in the fuel, but sugar stays crystalline instead of dissolving. We now believe it may be related to a reduction in FAME free fuel and a change in fuel and fuel treatment additives.”
In order to identify the culprit, Stephanie is keen to hear from boat owners and engineers with similar problems: “I want to learn more about their experiences, where they filled up and what treatments they may have used, and increase my sample size. The more I know, the closer I am to finding a solution.”
Stephanie believes the issue could stem from chemicals, now present in some treatments and red diesel, which replaced banned additives, and she’s looking into the farming sector’s blocked fuel filter problems reported around a year ago.
According to Farmers Weekly, in order to increase the proportion of fuel derived from renewable sources (capped at 7%), an increasing amount of biodiesel was blended with red diesel. Known as Fatty Acid Methyl Ester - FAME – it’s made from a combination of fresh and recycled vegetable oils and some animal fats.
The blockage problems were initially attributed to its storage, but differing regional cases discounted this. The UK Petroleum Industry Association (PIA) tested samples but failed to pinpoint a single cause. However tests by a fuel additive producer showed there could be a problem with insolvable particles dropping out of some of the fuel blends.
After testing 100 fuel and clogged filter samples, only 15% were found to contain contaminants as a result of poor storage, and in many cases, they weren’t significant enough to cause a blockage. The remainder were contaminant free with a clear appearance.
More detailed tests revealed the fuels had high total contamination levels and particulate counts, many between 15-20 mg/kg. Clean gas oil normally has a contamination level of 6mg/kg and the legal limit is 24. When an external lab tested the sticky residue it revealed the problem was caused by sterol glucoside and monoglyceride particles.
These substances can drop out of bio diesel components and the problem’s made worse at low temperatures. They can also easily accumulate as they don’t melt back into the fuel as the temperature rises. With FAME coming from multiple sources, the PIA says fuel producers are working to address the issues by changing the properties of their diesel fuel blend.
Stephanie continues: “There’s an industry task force currently looking at sustainability and the use of second stage bio-diesel for marina applications and they report these ‘sticky fuel’ symptoms were reported in their testing samples when using first stage bio-diesels. It’s clear there’s an ongoing problem which I wonder may be due to marinas no longer being able to supply FAME-free oil.
“It’s important we get to the bottom of the problem as these are costly breakdowns and business are also at risk due to the reoccurrence of issues and covering repairs under warranty.”
Stephanie is asking anyone experiencing ‘sticky fuel’ issues to send in samples or get in touch with River Canal Rescue: “Please give your name, email address, a date when the issue occurred, when you last filled up with fuel and where, plus information on whether any treatments were added to the fuel and if so, what type.”
Letters should be addressed to: Fuel Samples, River Canal Rescue, 11 Tilcon Avenue, Baswich, Stafford ST18 0YJ, email: with fuel issues in the subject line or call 01785 785680.