Hi, Where can I get Diesel fuel tested to identify contaminants?

Hi I have a boat which is fitted with 2 Factory Marinised "Peugeot" engines ( the same engines were fitted in the "Ford Granada" and "Peugeot 405" and have CAV fuel injection pumps, Both pumps have been diagnosed has having failed within a day of each other because of a sticky fuel contaminant which has left a tar like residue on the moving parts of the pump,on the inside of the fuel tanks and the fuel pick up pipes. I would like to know why the deposit seems to have been there for a while but it has affected both engines within a day I would also like to know if it ( Whatever "It" is )could have been filtered out.