This LRO reader emailed LRO.firstname.lastname@example.org to ask Andrew Varrall about rough running solutions on his Land Rover One Ten.
When I bought my 1991 ex-military One Ten years ago, my first job was to replace the N/A 2.5 diesel with a 200Tdi. The engine appeared to have had no major work carried out on it, and it’s certainly had none since. Apart from the cambelt, I do all the routine maintenance. I’ve driven it almost every day, logging about 10k miles per year and keeping a note of the fuel consumption.
The engine is usually a smooth runner but, about five years ago, it sometimes ran a little roughly on start-up. If I stopped briefly to pop into a shop, say, it would run smoothly. This would happen several times a week and would also happen in reverse; smooth then rough. Suspecting air in the injector end of the fuel system I changed the lift pump. It seemed cured at first but then the fault reappeared. The local main dealer said I should always use fuel that came with additives, i.e. Not supermarket diesel.
The engine was definitely smoother but still not right. I again changed the lift pump – but the fault persists to this day. There are never any unexpected variations in the fuel consumption and the engine pulls well. All filters and oil water separators are changed or cleaned regularly. I do notice that the fuel filter never really becomes full: if I slacken
off the bleed screw or the top union to the injector pump, I can’t get any fuel seepage out of them when pumping. If I stop the engine and take the top union off the filter and look inside the filter, the fuel is usually about 10mm down inside.
Do you think this occasional rough running and fuel level in the filter are connected or would you say that there’s another problem?
Colin Parr, Southampton, Hampshire
The fuel filter should be full at all times: it’s a sealed system to ensure no air gets in. If the filter isn’t full, that means air is getting into the system from somewhere and is the most likely cause of your rough running. You need to check all the fuel lines carefully for cracks or wear, check the injectors for leak-off and, finally, check the injection pump – which would need to be done by a diesel specialist. This is all assuming that your new lift pump isn’t faulty, of course…
This workshop advice appeared in the March 2016 issue of LRO. Back issues are available to download on digital devices here.