Engine cuts out with bubbles from injector

[SolarGuy]

Hi all, i need help with my punto van. its a 1.9 diesel which i recently purchased. it had been stood a while before i got it and has run ok for the last few weeks until today... the engine just died on me and when i looked under the bonnet there were bubbles coming from one injector, after about 5 minutes or so the engine fires up and is ok for a while until it cuts out again. ive had the injectors out, they seem ok so am at a loss. any ideas would be much appreciated as this is my work van lol

 

[Ffoxy]

Its blowing back, might need a new injector or the injector seat re-cutting. A specialist can measure this blowback for a fee. It causes the diesel to be pushed back from the injectors, causing fuel starvation.

 

[EI4GGB]

bubbles coming from where ? and which punto / engine exactly ?