Disco 1 Pressure inside fuel filter.

havent posted for a while, but I've got a bit of a strange one and think I might be missing something obvious.
Last week, after driving st a steady 60 mph for about an hour, my 300tdi slowed and died. It felt like fuel starvation. It would start after a struggle and tick over, but wouldn't rev at all. I ended up being recovered by the RAC.

I changed to fuel filter hoping it would be a quick and cheap fix, because it was well overdue for a service. As I unscrewed the old filter, fuel spurted out under pressure from around the filter head and filter seal. I'd never seen that happen before.
Anyway, with a new filter, the car started and run fine.

Yesterday, I was driving the same journey and broke down again, in exactly the same spot as I had the week before. Same symptoms. I was a bit low on diesel, so I got a friend to come out with a couple of gallon cans. While I was waiting, I unscrewed the new filter and found that it was under pressure again. I gave it a good rinse and shake out with the new diesel and put it back in. The car started and drove fine again. When I got it home, I emptied the fuel tank and took the sedimentor off. The sedimentor was almost full to the top with what looked a lump of old liver, lol.
I cleaned it all out and put fresh diesel I the tank and the car seems fine again now.

I'm just a bit concerned about the pressure in the filter and worried that I've missed something else and that I might break down again without warning. Bit times I broke down were on a very busy dual carriageway and it's not a nice feeling when you see 40 foot articulated lorries bearing down on you at 60 mph!

Any ideas and suggestions appreciated.

Hi Stevie
Filter in lift pump blocked ? return pipe to tank blocked ? Scrap the first bit as you wunt have fuel in filter
Steve

Must be a blocakge after the filter. Try blowing through leak back pipe (although a blockage here would, i think, cause the small injector leak offs to blow off).

Try the banjo bolt on the rear of the IP - its not a normal bolt - it has a tiny hole in the center of it. See if that is blocked.

Thanks for the replies. Will look at the return to tank pipe and the banjo at the back of the injection pump. If it was a blockage after the filter, why would it run fine again once the filter is replaced?

I dont know technical details, but that bolt on the back of the IP is specifically to maintain pressure in the IP.
I would imagine that, if it blocked, and the internal IP pressure went way out, then "stuff" could / would go wrong.

...who knows what, but it may give the symptoms youre on about.

...or it may be a complete red-herring. I dont know. But its so easy to check that hole, its worth a gamble, i reckon!

Yeah, thanks, ill have a look. Can you just poke a pin in it to make sure it isn't blocked, or is there something else I need to do?

Just take out the whole bolt (make sure you dont loose the copper washers) and blow through it.

...of course, you really want it to be blocked, as thats your issue then!

May as well blow back the return line to the tank whilst youre there - same area.

probably a faulty injector allowing compression gases into fuel system, introducing air into fuel system

freelance said:

probably a faulty injector allowing compression gases into fuel system, introducing air into fuel system

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In your dreams.

Check the filter where the fuel goes into the injection pump. It should have one if it's a none EDC pump..

I have cracked off each injector nut and noted the drop in revs, then the pick up when each was tightened. All of them showed a good show of diesel under pressure, plus, the car runs fine when it's not broken down, lol.

wammers said:

In your dreams.

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re
I 've changed injectors on 200 tdi for this very fault, bastard to remove as well when they're stuck!

wammers said:

Check the filter where the fuel goes into the injection pump. It should have one if it's a none EDC pump..

Click to expand...

Sounds like that could be the problem, except the car has run fine after the fuel filter has been replaced. Is that easy enough to do? I wouldn't know where to find it? It is a non EDC pump.

Steviecops said:

I have cracked off each injector nut and noted the drop in revs, then the pick up when each was tightened. All of them showed a good show of diesel under pressure, plus, the car runs fine when it's not broken down, lol.

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The lift pump applies a pressure to the injection pump. Not a great pressure but a pressure. When the engine is running the HP pump inside the injection pump increases the internal pressure to around 3 or 4 bars depending on RPM. There is a valve in the injection pump that controls this internal pressure and blows off at a preset level and returns fuel to the inlet side of the HP pump. When the engine is stopped this internal pressure bleeds of over a time through the fuel return system. If the filter is removed shortly after the engine is stopped it would not be beyond reason that fuel would flow from the filter.

freelance said:

re
I 've changed injectors on 200 tdi for this very fault, bastard to remove as well when they're stuck!

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I would be very doubtful that would have been the cause. How did back pressure from an injector if it existed get past the delivery valve?

Steviecops said:

Sounds like that could be the problem, except the car has run fine after the fuel filter has been replaced. Is that easy enough to do? I wouldn't know where to find it? It is a non EDC pump.

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If it is ok now after filter change leave it. There should be a mesh filter under the union that feeds the injection pump.

wammers said:

If it is ok now after filter change leave it. There should be a mesh filter under the union that feeds the injection pump.

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Thanks for the valuable information.