The Fuel Problem That Gets Misdiagnosed as Something Else
A fleet manager calls with a truck losing power and plugging filters, and the first move is almost always to treat for microbial growth. Sometimes that's the right call. Often, it isn't — and the fuel gets treated with a biocide, the problem doesn't go away, and everyone's back to square one wondering what they missed.
What's actually happening
Today's common rail systems run at pressures up to 30,000 PSI — roughly six times what older conventional injection systems saw, at temperatures around 210°F. Push diesel fuel through that kind of pressure and heat repeatedly, cycling back through the tank, and tiny tar-like particles start forming and sticking together. Those are asphaltenes, and they look and behave enough like a microbial problem that it's an easy misdiagnosis to make.
If the biocide didn't fix it, you're probably not looking at a microbial problem at all.
Why it's more common now, not less
This isn't a new fuel property — it's a byproduct of changes that were supposed to be improvements. ULSD is less stable and lower in aromatics than the fuel it replaced. Biodiesel blends hold more water. And modern common rail systems run hotter and under more pressure than ever. All three trends point the same direction: more asphaltene formation, not less, as equipment gets more advanced.
What to watch for
Filter plugging, reduced fuel economy, loss of power, and injectors that need replacing more often than they should — any one of those on its own could be a dozen things. Together, and especially after a biocide treatment hasn't solved it, asphaltenes belong on the list.
The Takeaway
A good fuel maintenance program built with your FPPF rep — using Fuel Power Maximum Formula or Total Power in winter — dissolves the particles and clears the water before they cost you a truck on the shoulder.