My Fiat Doblo 1.9 multijet (2008) would not start yesterday. The RAC chap said it was air ingress into the fuel lines. He removed the air out and it started fine. I'd like to try to find the source of the problem myself instead of taking it to the garage, in order to learn a bit about the enngine. Can anyone tell me the first steps I should take? Please bear in mind I have little experience with these things, but am a keen learner

if the air ingress was going to be a recurrence then looking for it there would also be a fuel leak. is it slow to start? does it smoke?

not knowing your car does it have fuel filter housing or cannister fuel filter? check the seal and fitments are tight. id also take quick look at injector seals, any wetness around injector area, and also fuel return lines from the injectors. they are the rubber pipes running along the injectors, they do perish over time and chafe on other components.

maybe a good solution would be a hand priming bulb to pressurise the system and look for leaks or hissing of air/fuel escaping, id fit it before the filter. or even turn the key to pre heat and listen for escaping air under the hood as the system pressurises.

how did the rac man remove the air, as these are self priming. and didnt he help with any diagnosis.