TD5 Fuel Pressure problem

sierrafery said:

1. Some time ago we spoke about that air bleed valve in the fuel filter head.... did u put a new one?(refurbishing the old one is not an option believe me) ....cos when the level in the tank is down there is more air accumulated in the fuel which must be eliminated(and that's what that valve does). As the car moves the fuel in the tank churns too and air is mixing in it. Take a bottle, fill it with diesel and shake it...then see how it looks.... empty it to half then shake it again...u'll see that's more air mixed in the diesel then. That's what happens in the reservoir too.

2. When the tank is empty the pump must have to struggle harder to send the diesel cos there's smaller pressure at the bottom of the tank....and if it's tired that might have an effect

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sierrafery said:

It's the rear outer pipe connection to the filter housing part nr. WJN500110, example Britcar (UK) Ltd > WJN500110 VALVE AIR BLEED ASSY TD5 DEF-DIS2 (G)

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chrimcne said:

Why can you not refurbish the old one - took mine off and pushed a pin through it but made no difference to the starting problem. However there doesn't appear to be much more to the valve apart from an O ring.
Yours puzzled.

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brainboy81 said:

It will be injector o-ring or the non return valve on the fuel filer housing. Try the housing non return first back left pipe about 6 quid if i remember other wise its the rings, not a too difficult job just time consuming.

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andrew j said:

I have done just about changed the whole delivery system on mine and it is STILL playing up below half a tank of fuel the only thing i got to change is the copper washers , will not be a happy teddy bear if it is still the same , new pump , pipes , fuel regulator , non return valve , and the air bleed valve !. is the "sling hammer" the same as a slide hammer ?.

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1. The filler is closed by a threaded plastic cap which screws into the filler neck. The cap has a ratchet mechanism to
prevent overtightening and seals against the filler neck to prevent the escape of fuel vapour. The filler cap has a valve
which relieves fuel pressure to atmosphere at approximately 0.12 to 0.13 bar (1.8 to 2.0 lbf.in 2 ) and opens in the
opposite direction at approximately 0.04 bar (0.7 lbf.in 2 ) vacuum.
2. A breather spout within the tank controls the tank 'full' height. When fuel covers the spout it prevents fuel vapour and
air from escaping from the tank. This causes the fuel to 'back-up' in the filler tube and shuts off the filler gun. The
position of the spout ensures that when the filler gun shuts off, a vapour space of approximately 10% of the tanks total
capacity remains. The vapour space ensures that the Roll Over Valve (ROV) is always above the fuel level and vapour
can escape and allow the tank to breathe.
The ROV is welded on the top surface of the tank. The ROV is connected by a tube to the filler tube, which in turn is
connected to the atmospheric vent pipe. The ROV allows fuel vapour to pass through it during normal vehicle
operation. In the event of the vehicle being overturned the valve shuts off, sealing the tank and preventing fuel from
spilling from the atmospheric vent pipe.

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CharlesY said:

I hear all these experiences, but I still wonder why my TD5 is fine when the tank is well filled, and gets progressively worse as the fuel level goes down.

I know this is an old post but I have recently had fuel issues with my 04 Td5 S2 Discovery.
To keep it short events were as follows
1 Ruptured high pressure fuel line.. repaired in Alice Springs
2 Low fuel in tank and hard to start
3 New non return valve in filter housing along with filter change.
4 Still hard to start and fuel aerated
5 Removed fuel pump after learning via another blog that there is a fine filter in the bottom of the fuel pump
6 Remove filter from bottom of pump and remove fuel gauge sender unit.
remove cover over main pump to reveal fine filter see attached photo
Reason for aerated fuel is when tank get low and fine filter is blocked the pump had to "source" fuel higher up filter hence air getting into fuel.
As pump was starved of fuel it cavitated hence the howling sound
Removed at least a half teaspoon of trash from fine filter before I washed it with household cleaner and blew it dry with compressed air.
Reassembled pump and refitted to vehicle, did bleed cycle and hey presto we had instant start and a vehicle that runs a whole lot better.
Hope this is of help to all out there because I do now wonder how many pumps have been discarded due to this filter being blocked
PS If this is of help to others and you wish to copy and repost I have no problems with that

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