FORD Focus C Max - Filter Failure
I used to have a Discovery with the 200Tdi engine and replacing the filter presented no problems. However, when I changed the fuel filter on my 2005 Ford Focus C Max 2.0TDCi, it was a different story. There was no problem changing the filter - it was getting the engine started again! My battery started to go flat from much fruitless cranking and only after buying heavy-duty jump leads (the old thin ones nearly melted) did it finally start, courtesy of my wife's Citroën C1.
I checked with a Ford main dealer who said that it was a common problem and they frequently had to resort to a slave battery as the battery flattened, to get the engine going.
Chats with two trusted mechanics confirmed that diesel engine fuel filter replacement re-starts are a problem. They both cited some Mercs as being particularly difficult, with sometimes the starter motor getting so hot that they were in danger of burning it out. The problem in all these cases is that the fuel pump seems to struggle to draw fuel through to the injectors if any air has entered the system; there is no air bleed screw on the Ford.
To finally get my car going, I made sure the canister housing was completely full of fuel, then disconnected the fuel feed line from the tank at the canister housing and put my thumb over the inlet while my wife turned the engine over. I think this reduces the amount of 'suck' required from the pump. After a titanic struggle, the car finally started and I immediately reconnected the fuel feed and there have been no further problems since. Any comments?
You are correct in that trying to start some diesel engines after a fuel filter change can be rather difficult. However, in many cases it can, to some extent, be blamed on the operator for not filling the container or filter body before reassembly. Your tip about holding your thumb over the inlet pipe is also a valid point, especially where steel pipes are used. However, when rubber hoses are used (such as on Mercedes) and access is okay, it's better to use a hose clamp.
On related point, I have heard of cases where the container is filled with a fuel cleaning additive instead of diesel fuel. This kind of treatment does the injection/pressure pump no favours whatsoever.