fuel engine stalling???

Hello all fellow landy lovers got a fuel problem the engine keeps cutting out I have consulted the haynes manual changed fuel filter put new lift pump on , engine was running good with old fuel pump on but had to leave the bleed nipple undone no fuel was coming out of the nipple when the engine was running thats why i got a new fuel pump now fuel comes out of the bleed nipple whhich is good because this means the old one was shoddy but when i tighten the bleed nipple the engine stalls when stopping in awkward places so am at a loss must be sucking air maybe cant see any visible fuel leaks and i have thick black smoke when going uphill doesn't seem to burn much oil at all but thats a job for another day. help cheers

Hi serious1,
Where is the bleed nipple located that you refer to?
In my experience the lift pump may fail but you will not notice unless you break into the fuel delivery system, i.e. change the filter, then the engine will not start. If your pump has a mechanical lift lever on the side make sure it is not jammed. The quality of some of these pumps is very poor, it may be worth trying another as you have not altered anything else.