UK Ford Repair Questions? Ask a Mechanic for Answers ASAP
its 1st worth considering fitting a new fuel filter as if only slightly blocked this can lower fuel supply pressure and choke the main pump, the pump will be more sensitive to this when its cold as diesel thickens considerably with low temperatures.
It may have developed an air leak on the fuel supply pipe from the tank to the engine. The engine has no separate lift pump and relies on the built in one in the injection pump. If a leak has developed on the fuel suction pipe then air entering the system will air lock the pump.Try pumping up the fuel using the hand pump in the engine bay on the filter housing, then crack off / loosen each injector pipe in turn while cranking the engine and getting an assistant to operate the primer. This will expel air from the injection side and the engine should fire up. The problem will be cured by checking the supply pipe along its length for signs of leakage and repairing any you find.
If you daub each pipe joint with heavy grease and the issue goes away then wipe the grease away one at a time to highlight the problem joint
the filter should be replaced every 20K miles in normal use but if you have been exposed to contaminated or dirty fuel then the filter will need changing a lot earlier
I'd recommend using a current clamp on the glow plug wires as the next step
but I do think the most likely cause is a lack of fuel coming through to the main pump
there's no return line from the pump and the lift pump on the back just draws it through the filter then into the pump
so any restriction on the filter or a leak on the line will drop the vacuum and prevent it from drawing the fuel through
it would also be worthwhile trying loosening off the filler cap as they have a 1 way valve to allow air into the tank and prevent a vacuum from being generated
it should have a set of glow plugs according to my records
and the oil and filter service is every 15,000km (9000 miles)
although if its looking very black I'd replace it regardless