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Discussion Starter · #1 · (Edited)
Hi Guys! Can I pose this Qq? here.
OK, it's a Mondeo TDCi I've got.. Wait! Don't go!... It has the same beating heart of an engine as all your X-Types with TDCi units... hopefully some of you just might have the knowledge I seek.....
I had to change the fuel pump as the one in it was tired and only delivering 850 bar, occasionally causing P1211 and P0251 and cutting out. I'd bought a replacement 12 months earlier and was just waiting for one of those roundtuits moments.
I'd previously replaced the fuel pump 3 years earlier for this slightly better 2nd-hand one, so knew how to do it, but now SWMBO decreed she wouldn't go in it till I'd sorted it.
Anyway, I changed it, and the engine ticked over fine, the new pump delivering a healthy 1200bar. Then suddenly after 10 minutes ticking over, the engine cut out. I checked everything and found the fuel filter was empty! I primed it again, filling the filter, and the engine ran fine.... until the filter emptied and wasn't being refilled. Anyway, lots of checking later, I've found that the pump isn't SUCKING any fuel from the filter only what's gravity fed into the pump. I rested a can of diesel on the engine and ran a clear tube to the filter inlet, part-filled the tube and ran the engine. No fuel is being drawn from the can.
I removed the pump, took it apart and half expected to find some paddles or springs missing in the low-pressure compartment, comparing it to my old tired pump, all the components are intact. So, I'd like to know if any of you has an idea what could be the matter. For instance, I don't really know whether the IMV has any control over the low pressure side (I did swap the IMV, btw) or what is the function of the venturi...., would a malfunctioning venturi or IMV result in no low-pressure side suction.... I'm at a loss. I attempted to refit the 2nd old pump, but it was late Nov/early December, freezing cold, I caught a cold and it affected my working, I ended up screwing up securing the pump sprocket, and the timing chain slipped! I then had to remove the timing chain cover (arghhh!) and attempt to retime the engine, whereupon I lost my mojo and as I felt really out of my depth... This all happened 3 years ago and the Mondeo has sat there ever since patiently awaiting my return. I now feel ready to have another go at it, but would like to know if anyone here has any experience with these high pressure pumps (they have 2 Chambers within-a low pressure and a high pressure one) there is NO lift pump on these either.- that's on the TDDI engine.
Anyway, if anyone is still reading this..... well done!
Meantime, I'm starting to sort out and recall what's to do and how I supported the engine on a jack without denting the sump pan,.. etc 3 years ago!
 

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Hi, don't know about the workings of the fuel pump but I recall seeing a video on youtube by Alan Howatt, a mechanic at a taxi firm who only use mondeo's. He points out a fault with a component of the pump rather than the pump itself. Google fuel pump mondeo and you will eventually find his channel, may be worth a look.
 

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I expect you changed the filter. Give the water drain on the bottom a really good tighten, I have had 2 of these new Bosch filters on customer cars let air in but but no fuel out. Then a cracked housing on a Nissan Van do the same thing.
 

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Discussion Starter · #5 ·
Hi x-files! Thanks for replying!.. I'm in process of putting it all together again after nearly 3 years in bits. Just refitted chain and sealed the cover. Used your tip from another forum to locate the cover accurately with studs.... Top tip! 👍, as Ed China would say.
The 'new' pump didn't have any suction on the low pressure side, so the engine ran until the filter emptied. I even put a can of fuel on the engine with a clear pipe to the filter input and got a minimum column of fuel - there wasn't enough suction to draw any fuel into the filter from it. Would the IMV have any effect on the low pressure side? If for instance, a wire has broken inside the insulation what would be the result?
Have refitted previous tired pump to see if it works OK with that, to retrace my steps and start again, so to speak. Work in progress....!
 

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Sorry missed this. If the IMV has no power then it is full open and builds max pressure on the rail 1800 bar ish.
If the filter is sealed it can not empty, also if there was no suction it could not empty, is the return line sealed up, are you sure you have the filter connected the right way round -seen that done by a garage! There are arrows embossed on the filter.
There is not a huge flow rate through the pump.
 
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