Air getting into the fuel system anywhere between the fuel tank and the injection pump is the most likely cause. Thoroughly check all rubber fuel hoses for signs of perishing, and also check the fuel filter and housing. Air is getting in somewhere, and you need to find where. You could do much worse than to replace all the fuel hose on the vehicle.

Another cause could be the build up of dirt inside the fuel tank which collects at the fuel outlet and blocks it leading to fuel starvation. Unfortunately all fuel tanks regardless of what they carry will contain dirt and water. You cannot prevent this because of evaporation and condensation. Algae forms inside the tank if water is present. Use an airline and very gently blow back into the tank from the fuel pipe which takes fuel into the fuel filter. If you feel a resistance which suddenly clears you will know there is dirt in the tank.

The secondary fuel system is from the injection pump to the injectors. Air cannot get in here because fuel is pushed by the pump, not drawn. Don't expect fuel to wildly spray out when you loosen an injector pipe because there will not be much pressure. Pumps do not create pressure, they facilitate flow. Opposition to flow creates pressure, and that opposition point is the injector nozzles.

If the engine stops suddenly, just as if you switched it off then the problem could be a faulty fuel stop solenoid.

Edited by Railroad. on 15/10/2015 at 17:49