Hello I'd check that you're getting full power to the glow-plugs, they pull a lot of current so take care when checking but see if the relay is clicking when the ignition is turned on first and also check the fuse if this is OK check to see if the engine earth strap is also OK. You can test the glow-plugs with a multimeter by measuring the resistance across the plug ( between the power connection and the body) it should be around 4-8ohms if its tending to infinity / open circuit the plug is faulty or by using a clip on current clamp, either on the supply wire to glow plugs or onto engine earth, with glow plug light on you should see 15-20amps for each glow plug fitted, 4 cylinders would be approximately 60-80amps.
Also if its not injecting at all then check the connections to the crankshaft sensor, unplug it and check for corroded contacts and broken wiring, and consider fitting a new sensor - do the same for the cam position sensor
If the EGR valve is stuck open then this too can effect starting so try disconnecting it to see if this helps or changes anything
Could also be an injector leaking fuel back through the overspill pipe, so not getting enough fuel pressure to tell ECU to fire the injectors, this is trickier to find and you’ll need the garage to do a ‘run back’ test to identify which one is the issue
Lastly it’s also worth considering fitting a new fuel filter as if only slightly blocked this can lower fuel supply pressure and choke the main pump, the pump will be more sensitive to this when its cold as diesel thickens considerably with low temperatures.
Can you please let me know if the private VW expert is correct in saying that the Main Engine Dirven Pump is defective?
On a cold start he found low fuel flow coming out of 1, 3, 4 Fuel Lines when he checked the fuel pressures between the Main Engine driven Fuel Pump and Injectors on cold engine?
The car only two years with 16,000 km done and the Pump replacement will be fairly painfull?
HelloOK if the main pressure is slow to build then yes its possible the pump is damagedhowever I really would replace the filter before anything else as this is pretty fundemental to the main pump working properly plus its cheap and easy to doif its still slow to build then before jumping into a pump replacement ( as yes this is expensive at about £800 for parts and a few hours labour) ask about the 'run back' test I mentioned above as a set of injectors are cheaper than a pump
if this shows the injectors are OK then sadly yes its then time to replace the pump
Thanks, someone had mentioned that leaky Injector Seal may intermittently allow air into Fuel lines when cold.
Is this a possibility?