Car was running with little power, especially up hills, after a month of this, car wouldn't start.
Checked these basics first. Car needs Air, Fuel and compression to run.
** Air Side **
air filter not blocked (Run without filter in, see if it's better)
Turbo turns freely, and not worn.
air pipes/manifold not blocked, or leaking
MAP and MAF sensors working as they should do (volt meter, or OBD)
Check glow plugs all come on and resistance 0.8 to 1.2 Ohm. (my other video)
Check glow plugs aren't loose (no/low compression)
Check crank sensor pickup
Check fuel pressure sensor

** Fuel side **
Low pressure pump working (listen for it Pos 1 & 2 of ignition)
Fuel filter not blocked, or full of water (usually a drain underneath)
Fuel in High Pressure rail
Injectors fire (my other video)
injector fuel return test (leak down test)

Anything else?
A few of you want these details...

https://www.ebay.co.uk/usr/dieselexch...