Starting trouble/Air lock in fuel system

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Hi Guys,
I have been having a starting trouble on my ford mondeo diesel 1.8 Tdci, mk4. Once the key is turned, the engine starts at first but then the engine shuts down as if no fuel and then it cranks but does not start. After a few tries starts but then I have to press the full gas to get it going normal again.
Initially this used to happen when the car was parked on a slope (front up). Now I can see it happen normally.
Once, I had to call RAC help and he had suspected that I was having an air lock issue in the fuel system. Following are the observations from his report -
“cranking non start - vehicle parked on slope
fault code present for fuel pressure control valve
primed fuel filter using hand primer and reset fault code. fuel pressure came back and engine started.
suspect fault in system causing an air lock”
Did anyone experience this problem before? What’s the way out?
Many Thanks

Is there a pump which can have priming issues?

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I've got a MK2 Focus with the same engine and years ago when I 1st serviced it I had a few problems with getting it restarted.

The 1.8 TDCi doesn't have a "lift" pump in the tank so if there is anything more than the tiniest amount of air within the fuel system it won't pump fuel.  The main area of possible weakness I found was that the rubber seal that sits with the fuel filter itself (within the steel fuel filter casing) is easy to not site properly when fitting the filter.  This can allow small amounts of air into the system and making restarting difficult or impossible, it's also been known for some garages to forget to fit the seal.

The other related issue I once had was where I must have not sufficiently tightened the "lid" on the fuel filter housing when I serviced it, the car ran fine for a few days but the vibrations from the engine must have "encouraged" it to work ever so slightly loose which allowed a tiny amount of air into the fuel system, this caused the car to conk out on a motorway slip road.

Because a genuine filter is only about £7 on ebay and it will come with a new rubber seal, I'd be tempted as a starting point to just replace the filter (if it hasn't been done for a while it'll be ready for being replaced anyway).  Even if it doesn't fix the issue you'll at least have a nice clean filter and working seal so it's an area you won't have to touch for a while going forward.

Incidentally, if the pipework after the fuel filter gets full of air it can be a royal pain in the ***** to get started again.  Me and few others on here have found that filling up the filter with fuel whilst it's fitted in the housing (before the "lid" is fitted) helps avoid the air locking issue.  If the fuel rail is already air locked you might need to do it 3-4 time before getting all the air out.

I'm sure there have been a couple of threads on the Focus thread specifically about this issue, it might be worth looking as there are more detailed guides as to the steps taken to "bleed" the fuel system.

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