Fuel vacuum cap breather 306 hdi

[Welshy_Pete]

Hello I changed the fuel filter due to being a little black and due for a service on my 306 hdi in the engine. I then had to clean out the fuel strainer in the tank due to cutting out. The strainer was blocked up so give it a good clean out. Also cleaned the diesel tank of the bits while sorting that out.

I did prime the pump and leave for so long a few times. I did hear the air or bubbles clearing up then normal primes on both times fuel filter changed and fuel strainer cleaned out.

The car run ok after but after 60 miles or so. But it started again the car stopped last night. I was there for a few mins and thought I try open the fuel cap. So as soon as I did this the car started up and run perfect all the way home 20 miles. I could hear vacuum noise when I open the cap to.

The car might run ok now but unsure until I drive about much longer then maybe fuel cap of again who knows.

So I'm thinking did it clear the air out the system, the breather need cleaning or blocked?

Where the breather system located?

Thanks

[Welshy_Pete]

So do we have any ideas?

[Stickyfinger]

Your CAP breather hole is blocked and you are making a vacuum in the tank, hence the air sound.....clean out the hole in it

[RichardW]

I'd expect there to be a proper tank breather rather than just a hole in the cap. Could be wrong though...

[Welshy_Pete]

Your CAP breather hole is blocked and you are making a vacuum in the tank, hence the air sound.....clean out the hole in it

I thought this but cleaned the cap there no holes in the cap.

[Welshy_Pete]

I'd expect there to be a proper tank breather rather than just a hole in the cap. Could be wrong though...

I've just found out breather system will either be blocked or the one way valve is knackered. Breather system runs along the front of the tank from the centre of the car to join the filler neck. Also the one way valve is part of the system on this part to.

[citronut]

im sure you may have already sent me your cars chassis/VIN No. before, but i dont know were it would be,
so if you send me it i will get you a screen shot of your tank vent system from pug service box,

on the two i looked at it seems the tank vents into the top of the filler neck just below the cap, this suggests to me there will be a vent hole in the cap, it could well be concealed

[spider]

Seems to be vented (diesel models only obviously!) via the pipework. Choice of two, either with or without a non-return valve although they do not look too dissimilar:

306 Diesel N5 WIthout Return Valve:



306 Diesel N5 With Return Valve:



For what its worth I looked at the old shape ones out of interest and it seems only the early ones vented via the cap (as there appears to be no venting hose) but later first shape ones have an almost the same setup as the newer shape ones.

It just lists Diesel / Petrol etc for the new shape there's no distinction with engine type ie DW8 / XUD9 / XUD9T / DW10

[Welshy_Pete]

I went to test the car out there no miss in fuel now so the filters are working fine now.

So when doing 30 miles going up a hills it would cut out. There plenty of fuel in the tank I know.

But when I loosen the fuel cap so not tight it never happen again up any hills for 30 miles. So it must be a vacuum problem for sure.

I had a look underneath the one way valve on the breather pipe can that be seen without removing the tank?

[Welshy_Pete]

I was thinking it sounds like a lot of work just to change a one way valve when I can just do the fuel cap not so tight......

I thought so is that much of a job to take the tank down?

Some people say drill a small hole in the fuel cap or best just loosen the fuel cap slightly.

The fuel cap I tighten it right up then loosen it slightly to vacuum can work but no dirt get inside. This should be ok as long as the fuel tank not filled right up?

[Stickyfinger]

Drill a hole....IF (god forbid) you have an accident, the last thing you need is fuel spilling all over the place........be safe mate.