Hi - Anybody come across this - we're a repairer and we have a car in that was experiencing severe diesel knock and some over revving when driven under load or revved up in workshop. We found grey gunge/some emulsification of the diesel in the injector rail when we inspected and renewed the pressure sensor. Renewal of the sensor has fixed the sympton (the knock and over revving) but we cannot explain the emulsification. We were thinking that perhaps the diesel could mix with the coolant in the FBH but felt this would be unlikely as the coolant would drip into the burner and out the exhaust - there would not be enough pressure to make the coolant enter the fuel system through the burner jet?

Might this be due to use of 'FAME' biodiesel which is hydroscopic, so source of water not the rail etc but in the tank? Q checking the rest if the system and asking where the customer sources the fuel. Only Range Rovers since 1988

+1 for fuel contamination. Probably water in tank. Complete flush needed me thinks.
Let us know what you find. Good luck 2007 Vogue TDV8 in Zermatt Silver with Charcoal

You won't get water into the fuel via the FBH as it's a separate fuel feed and I'm sure there isn't a fuel return to the tank. 2010 4.4 TDV8 Vogue SE

Source of fuel varies so no common link there. Have flushed pipework and sent him on his way with a new rail pressure sensor and a bottle of Wynns biocide to help break down any bacterial presence. Probably should have added some Wynns Dry fuel and also sucked tank clean but the labour content on some jobs just isn't fully justified for some peoples budgets????