Air in fuel system, discovery 300tdi

Hello, I'm having some trouble with my discovery 300 tdi. Firstly, I have very limited mechanical knowledge, secondly I'm skint! It started running poorly a few months ago, cutting out occasionally at junctions, since then it's got worse and worse, to the point it wasn't drivable. I changed the air and fuel filters a fortnight ago, and treated it to some diesel magic, which seemed to give it more pull, but the cutting out and slow starting was still there, so I changed the lift pump, which has made an enormous difference..... but it still cuts out and takes ages to start. No matter how much I try to bleed it at the filter, there is still lots of air in it, same at the injectors (incidentally, when injectors 1 or 2 are disconnected it doesn't run any different, when 3 or 4 are disconnected it knocks and splutters, don't know if that's relevant?) Please help!!

Try swapping injectors 1 & 2 over for 3 & 4, and see if it does the same with different injectors on the ends. Sounds like dodgy injectors. Soak them in injector cleaner or Redex for a day or so and refit. 2nd hand injectors aint too much if cleaning them up doesn't work.

leaky leak off pipes

Have you fiddled with anything else other than what you have listed?

Are the pipes on to the lift pump definately the right way round?
Is the lift pump installed properly, mating face flat to block and correctly bolted?

More importantly - did you turn the engine to TDC (top dead centre) before removed the old pump and fitting the new one? If not.............

If not any of the above Id be looking at a blockage in the return line and/or a problem in the tank.

read your post one more time;

A stretched cambelt or incorrect fuel pump timing would cause all the problems you are referring to - It sounds exactly like the engine to fuel pump timing is off

I had the same problems, and after much f**ing about , it turned out to be an air leak at the sedimentor.... it wasn't obviously leaking fuel, but a strip down and new seals cured all the problems..... try bypassing it first to see if it cures it.

Dave

there is another thing you could check out is the sender in the fuel tank the conections corode try giving them a thick covering of grease it will stop it drawing air if corrosion is getting too bad

i had same problem am running mine on bio fuel first bought new lift pump this cured it for about a week then more air again so replaced fuel lines and this worked well for about 2 weeks i ran it straight from the tank to lift using 8mm copper pipe from b n q then i had same problem again the new lift pump got a filter inside cleaned that out nd finally it going alot better , im just wondering about how to clean my injectors or a recommened vehicle to use them off #;0