Can't bleed air out of Mondeo Mk4 fuel lines

[dagsky2018]

Hi all, hope i can get some help with not being able to get to get the air out of my mk4 mondeo. This is the 2.0 diesel with the PSA (QXBA) engine in it.

Background story - Was out of town and i had a leak off pipe leaking, previously a tiny leak which then obviously grew bigger! I tried to change it and in the process managed to snap the connector, called a mobile mechanic, had to pop up injector rather than faffing about and risking breaking the nozzle inside. During this process i mentioned to him that the only way to get this motor started in the morning was with a shot of easystart, he then took off what i think is the Fuel Pump Pressure Regulator Control Valve, cleaned it and put it back.

Tried to start it twice, wouldn't go and he saw air in lines, tried to bleed first from the return pipe and after 10 min of not being able to clear it properly said he needed a bigger pump and then vanished! Called RAC out, he tried to bleed it through return as well, no luck, then tried through the other pipe next to the return and no joy. Gave up and towed me back home.

Now i'm trying to do it myself, i have tried using a tyre extension valve on the schrader valve to bleed it that way but every time i manage to get fuel up to the top and pull out the extension the fuel just drops back down as though it loses its vacuum or whatever is supposed to keep it from running back down.
Then i tried a modified contraption with a vacuum cleaner to bleed through the return line, lots of air pockets sucked up and fuel going to the high pressure pump but i noticed that after 10 min of this i still didn't have a solid line of fuel through the pipes and once i stop the suction it just drops the fuel back down.

I have no idea why its doing this when it previously wasn't, only things that have changed is the injector came out and the valve thing. I'm not even at the cranking stage so i don't see why it's losing the vacuum. Additionally i noticed the white locking tab and the one fuel line is missing, this was missing after it had a service and not during this incident.

Edited by dagsky2018 on Thursday 26th March 12:02

[GreenV8S]

It sounds as if you are dealing with a leak allowing air into the fuel system, rather than just bleeding out a fixed quantity of air. So you need to find the leak.

[Desiderata]

I had similar problems with a Focus TDCI after changing a fuel pipe, eventually fitted an inline squeeze fuel pump. Just left it on and it has been fine since.

[RobXjcoupe]

Just an idea, when bleeding do you have the fuel tank cap on? If so try bleeding with the fuel tank cap removed

[dagsky2018]

thanks for the replys guys, i've tried to look for any diesel leaks and i don't seem to be able to find any in the engine bay nor underneath the car, i assume that if air is getting in somewhere then it's got to leak diesel somewhere ( i think!)

This car has a capless fuel system so no fuel cap to take off unless i stick the funnel thing into it?

[GreenV8S]

dagsky2018 said:

i assume that if air is getting in somewhere then it's got to leak diesel somewhere

Not so - a hole that lets air in won't necessarily let diesel out, and if it's letting air in it will be under suction rather than pressure so even less reason to see a diesel leak.

[dagsky2018]

any advice on how i can go about checking?

Another thing i just wanted to check (i'm a complete novice at this and would like to try & resolve it if i can before chucking in the towel!) i'm not sure if i am bleeding this the right way. I've seen a few youtube vids that show people connecting to the fuel return pipe and then using a hand pump to try and pull the air out, one end is connected to return pipe and the other is going into a container to catch fuel. Is this the correct method?

https://youtu.be/Tmr1yhD-k5s?t=332 from 5min 32sec. I even bought one of the 12v things that he has but no joy.

[sunbeam alpine]

• *WARNING*** I have only tried the following method on forklift trucks and telehandlers - but it works every time.

Our machines run out of diesel a couple of times a year - combination of infrequent use and dodgy/missing fuel gauges, plus incompetent operators (usually me).

What I do instead of bleeding is to pressurise the fuel tank using a small compressor - you can wrap a rag around the pistol to get a seal round the neck of the tank - and crank the engine at the same time. I'm not putting silly amounts of pressure into the tank - just enough to force the diesel through the system. In your case, if there's a leak it may help to identify it.

All our machines have steel tanks - I've never tried this with a plastic tank.

Maybe worth waiting a bit in case someone comes along and says that it's dangerous/stupid with a car!