Problem: Failure in service of an industrial vehicle (forklift truck). Upon stalling, vehicle engine is unable to crank.
Discussion: The red diesel recovered from the vehicle’s fuel tank exhibited both the presence of a non-miscible liquid, in addition to solids, both suspended and settled. The solids had formed in a very short space of time (<48h). A baseline bunker sample was provided, along with the fuel filter and the separator.
Solution: The clear non-miscible liquid present in the sample was confirmed to be water by Karl Fischer auto-titration, which would be the primary cause of the engine not starting. The attention then shifted towards the solid material; IR testing found the material to appear similar to a natural amide, potentially indicative of bacteriological growth. Testing for the presence of bacteria, fungi and yeasts was performed on the contaminated diesel sample, with the bunker sample and a blank used as reference. After three days of growth, the contaminated sample exhibited significantly more growth than both the control and blank.
It was speculated that the rapid biological growth may have been the result of the presence of a feedstock, e.g. a sugar, and that foul play might be at hand. A residual sugar presence was confirmed by refractometer, indicating it likely that a soft drink may have purposefully been introduced into the vehicles system.