Land Rover Repair: 96 Disco 300 Tdi - air lock problem?, rubber hoses, fuel leak

Question
Hi John,
Thanks for looking at this question, I just replaced a turbo
intake pipe on my Discovery 96 300 auto tdi and i'm only able to
drive 200 meters or so before the thing cuts out, it's difficult to
start too, so i'm guessing air lock, if it is air lock how do i clear
it?
Thanks again.
Chris (London)

Answer
Hi Chris,

here's something I found that may be of interest:

"Air can cause numerous problems with the diesel engine and is one of the hardest problems to solve. The best way to determine that air is the problem is to hook up a clear hose in the return system. If air is coming through the return system then it is probably getting into the system on the inlet side somewhere and causing problems with the fuel system.

Air can enter the system two ways. The first is a bleedback where air is evident after the engine sets inoperative for a period of time and the fuel drains back to the tank and the system has to be reprimed. The engine may or may not start but if it does start it may only run a few seconds, die and refuse to start immediately. The lift pump is one of the most common causes of this situation, however any opening in the fuel system can allow this situation.

Constant air out the return and constant rough running, missing and white smoke can also be an indication of air in the system. In this situation air is usually entering the system somewhere prior to the pump inlet. If a fuel leak is evident this should be checked and repaired first, however a fuel leak does not necessarily have to be evident where air is entering. Sometimes the fuel system can be pressured up by an external fuel pump. If a fuel leak then becomes evident this could be the source of the air leak. Visual inspection of rubber hoses, line fittings and steel lines where they have been rubbed should also be made to isolate the source of the air. "

If your engine starts but stalls short thereafter, it could be one of the following:

plugged or restricted return;
insufficient fuel supply;
shutoff solenoid fault;
poor fuel quality;
bad injection pump;
idle speed too low;
idle solenoid faulty;
air in fuel.

I hope this helps,

JohnMc