Land rover wont start when facing uphill

Got a 2005 defender TD5 67000 miles owned for 5 years, been fine spot on couple of months ago fuel pump started making a load of noise had this replaced, since then failed to start any time and temperatures on first key turn always started first turn before. So then had new fuel filter housing still got same problem. Then had injector harness and rocker gasket. Since then if left on a hill for more than 5 mins wont start takes a good 20 turns to start like it is full of air. When it does go it drives a few yards then judders to a stop and then takes a lot to start again but when running spot on and loads of power no bother never misses a beat no miss fire. Then had new one way value to stop diesel going back still no difference anyone got any ideas. New pump working fine and fuel regulator not leaking.
Had injector copper washers done last week and still the same any ideas anyone?

Sure this was covered not long ago?
Some sort of 1 way valve gone all 2 way on you?

Something similar in last three weeks, suggest a search is on the cards

He's had the one way valve replaced.

Could try purge mode (turn key to running position but do not try to start engine. Press throttle to floor and release five times, you have to start doing this before the EML light goes out)

The fuel system will then self prime and while this is happening the red LED light on the speedometer will flash. The process takes about five minutes and you will hear the fuel pump start and stop.
When the LED stops flashing it's done. Turn ignition off then back on.

Worth a try.

If playing up since new fuel pump fitted thats where you need to start looking, purging the fuel wont help fix the underlying problem.
Im not sure on a defender but on the disco td5 the fuel pump/sender pipe fittings are speed fittings with small o-rings.
Iirc on a disco it is actually possible to mix the pipes up!