Diesel pump trouble

vanny · Post by **vanny** » 12 Jun 2006, 23:14

for a good 6 month now i've been going through a long winded process of having to prime the fuel system to start the car. Obvious thing to check was the piping for air. Thoguh issolation it doesn't seem to be the supply pipes return pipes or leak off pipes, i've also changed the priming bulb to a brand new one!

When primed up nice and firm, it takes about 4 seconds before you start to hear a hissing noise thena few seconds later there is a gurgling noise. The hissing sounds like its down the back of the pump and the gurgling sounds like it comes from the dome on the top (i realise there is no fuel in or near it).

I'm thinking that something in the pump has failed, but i REALLY dont want to have the car into bits all over again! Anybody have any bright ideas?

(Xantia Bosch pump, thus far hasn't been messed with at all!)

Allanxantia · Post by **Allanxantia** » 13 Jun 2006, 09:55

A couple of things to check. I have had problems with leaks around the fuel filter housing, and also I have seen the stop solenoid leaking at thw top. Try stripping down the fuel filter housing and re sealing it all.

vanny · Post by **vanny** » 13 Jun 2006, 13:04

Cheers for that allan, looking like the best bet is a long fine strip down and rebuild of all the attached systems, just really hope i can find it, 6 months of having to prime before travelling is very annoying!

goldfinche · Post by **goldfinche** » 13 Jun 2006, 19:59

Hi Vanny how you doing? Yep under the "dome" thingy on top of the pump is a diaphram if this leaks at all internally then, as it is pressured by and reads the turbo air pressure, it will put air into the pump. If you blank off the air feed to the diaphram and it helps the problem then at least you will know your heading in the right direction. Check the throttle spindle/bush for wear and any leaks etc.
Cheers.
Geoff.

Dave Burns · Post by **Dave Burns** » 18 Jun 2006, 10:12

The scenario suggested by Geoff isn't possible, because the cavity below the diaphragm is vented to the atmosphere, if the diaphragm is holed the air will just go through and out of the vent.

Because the fuel is under pressure within the pump body, allbeit relatively low pressure, if there is a way in for air, the same leak will almost certainly be a way out for fuel, so if there are no fuel damp areas around the pump it will be very unlikely that air is also getting directly into the pump body.

Dave

goldfinche · Post by **goldfinche** » 18 Jun 2006, 12:37

Ta for putting me right, sorry,cant see a vent but that dosnt mean that there isnt one.
As the fuel is under pressure what stops it from comming out of the breather?? IIMC if the diaphram is removed then you can see into the body of the pump.
Concidering that I cant remember yesterday etc.
Cheers.
Geoff.

Dave Burns · Post by **Dave Burns** » 18 Jun 2006, 14:24

The cavity below the diaphragm is dry, it is created in the casting and houses the diaphragm return spring and adjuster nut, the shaft with the control cone ground onto it (that the diaphragm is screwed to) and the guide pin that rides the against the cone.
The inner end of the guide pin is the only part inside the cavity that is in contact with fuel, this pin is sealed with an "O" ring to prevent fuel entering the diaphragm housing.

The vent is located at the rear of the pump just below the diaphragm, there should be a small rubber elbow attached to it pointing downwards.

Dave

goldfinche · Post by **goldfinche** » 18 Jun 2006, 16:02

Hi many thanks for the reply, I must have a problem begining to happen, there is no rubber elbow on the vent, and its showing signs of a leak. Oh well I needed something to do.
Cheers.
Geoff.

HST · Post by **HST** » 22 Jun 2006, 14:01

I had a similar problem with an unusual solution.

http://www.frenchcarforum.co.uk/forum/v ... 986#122986

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