My 2011 Ford Ranger XL 2.5 diesel is hard to start on a cold engine, it takes about 10-15 attempts before is starts. On a warm engine it starts like a charm. I have changed the fuel filter and glow plugs and still same issue, what could the problem be?
Normally this would be an issue with the glow plugs, but the 2.5 turbo-diesel Rangers seem to occasionally have an issue with the assembly around the fuel filter (which includes the water trap and primer pump) sucking in air. This can be fixed by replacing the unit as a whole. Similarly Ranger owners have reported trouble cold-starting their 2.5 TD when the valve stopping fuel flowing back into the tank from the pump fails. Try priming your fuel system a couple of times before starting and if it starts up fine then replace that valve near the fuel pump.