2010 vw caddy TDI mystery start/non start issue

[Dexy661]

Hi all, I recently purchased a VW caddy TDI which usually starts instantly first time. However occasionally it will start and instantly conk out, when this happens it will then not start again after unless started on easy start and then all seems fine again until the next time it happens.

Previous owner doesn't seem to have any knowledge of the issue.

I had a full service and cam belt done shortly after purchase, was wondering if it could possibly be a knocked sensor or something? Any ideas appreciated, thanks

 

[Dexy661]

Still having this issue..

Ive replaced the battery but still seems to die off after a couple of cranks when this issue occurs. Charging voltage seems to be ok when the engine is running so I assume the alternator is ok?

It only conks out on start up when the vans been sat for a couple days. If its been started recently it will always fire instantly and run fine.

Occasionally it will start and have a lumpy idle for a few seconds (when its been sat) I think this is when it just about stops itself from conking out. Giving it a few revs on start up also seems to reduce the amount of times it happens.

So im wondering if this could be some sort of fuelling issue or air getting in the system?

Fuel filter and fuel pump relay has been changed

any help appreciated, thanks