C5 cut out while driving UPDATE

Gazzaman22 · Unread post by **Gazzaman22** » 13 Oct 2022, 14:13

C5 II 5 DOOR SALOON 1.6 HDi 110 particle emission filter (DV6TED4)

Recently and randomly while driving my car will
cut out for no reason. And will not start unless I
stop completely and turn car off and then
restart. On the restart it might take approx 3
seconds to fire again but it generally does start
again.
I ran a OBD simple scan that I have on it and and it
gives an error about a large fuel leak. But I can't
find such a leak. Fuel filter was only replaced 6
months ago so I don't think it might be that. I
have access to another car for parts what do I
swap out first?
Fuel sender or is there a fuel pump?
Thanks

Unread post by **KennyW** » 13 Oct 2022, 16:08

Do you have access to a Diagbox ? If so do a global test and obtain the fault codes. From that members on the forum maybe can help.

Kenny

Gazzaman22 · Unread post by **Gazzaman22** » 13 Oct 2022, 22:12

No, sorry don't have access.... this is all I have at the min

Gazzaman22 · Unread post by **Gazzaman22** » 23 Oct 2022, 17:55

UPDATE- So the first instance of this happening fairly frequently happened 10 days ago after a fuel refill approx 40 litres - As i say it would just cut out while driving randomly(could do 5 miles or 2 miles) and always restarted.... as the tank empied the frequency of the of the cut outs reduced.
This morning i drove 50 mile journey to destination on round trip i done 40miles and it never happened once. I needed to refuel - 40 litres again(different location to previous fill) and was to contiue the last 10 mile or so home - in this 10 mile journey bang! Cut out while driving about 6 times.....
Got home and was having a look around the engine and ive noticed the priming bulb is sucked(kinda collapsed) in on its self - anyone know what going on here? Same error on my cheap OBD reader as above.

Hell Razor5543 · Unread post by **Hell Razor5543** » 23 Oct 2022, 17:59

That suggests a vacuum. I would check the fuel tank breather (wherever it is!), as if this gets blocked the vacuum can affect the fuel flow as it gets used. If it is quiet where you are listen very carefully as you take the fuel cap off, and if you hear a momentary 'hiss' that would indicate air being pulled into the tank (best to do this (if it is safe to do so) just after the car has cut out).

Gazzaman22 · Unread post by **Gazzaman22** » 23 Oct 2022, 19:47

Hell Razor5543 wrote: 23 Oct 2022, 17:59 That suggests a vacuum. I would check the fuel tank breather (wherever it is!), as if this gets blocked the vacuum can affect the fuel flow as it gets used. If it is quiet where you are listen very carefully as you take the fuel cap off, and if you hear a momentary 'hiss' that would indicate air being pulled into the tank (best to do this (if it is safe to do so) just after the car has cut out).

Will check that out tomorrow - Good Question "I would check the fuel tank breather (wherever it is!)" Anyone any ideas

If air is getting into tank, how does that affect the priming bulb and cause it to collapse?
I do have a spare car to pull parts from, Would it be a wise move to swap out the whole sender unit(perhaps its on it?) or/and the primer bulb(if it can be changed)

Hell Razor5543 · Unread post by **Hell Razor5543** » 23 Oct 2022, 19:57

I think you may have misunderstood what I meant. You want air to get into the tank to compensate for the fuel coming out. If the air breather is blocked that would allow a vacuum to build up, as the fuel is sucked towards the engine. The air breather is normally close to the fuel filler.

Gazzaman22 · Unread post by **Gazzaman22** » 23 Oct 2022, 20:17

Thanks Hell, Anyone know where the air breather is located, or what it looks like

Gazzaman22 · Unread post by **Gazzaman22** » 21 Nov 2022, 22:09

Evening all VIN VF7**************[VIN obfuscated, can be read by forum staff]
So my heads gone with this. We are finding it so strange.
There is air getting into tank, as when i open the tank after driving the is a small gush of air out of the tank- continuing with a small bit of Gurgling in the tank as the engine runs.
So a recap- if i have more than approx 10 litres of desiel in the car -- it seems to pull the desiel back to the tank causing starting issue and a soft priming bulb needing to prime the bulb.
What all we have done so far to try and fix-
-Replaced the priming bulb
-Installed a non return valve after the Priming bulb on the fuel line after the priming bulb
-I took the sender unit out of an old car(same) cleaned it totally out(Strainer as well) and installed it.
-Give it a service and new Fuel filter

We cant find a leak, and are wondering what out next move will be if anyone has any ideas, I cant get my head around why its fine with 10 liters or under but 20/30/40 seem to exacerbate the problem. We havent seen a Desiel pool or leak anywhere.

The small clips on the fuel lines entering the sender unit are they hard to replace or is it a new fuel line job? as i broke one of them - it is seated fine and nice and tight, but its bugging me slightly - i know its not the issue as the problem was there before i broke clip, but if it was easy to fix i'll do it.

Hell Razor5543 · Unread post by **Hell Razor5543** » 21 Nov 2022, 22:30

Are you sure that is air gushing OUT? Next time it happens securely hold a length of string close to the filler cap, and see which way it moves as you open the cap.

Gazzaman22 · Unread post by **Gazzaman22** » 22 Nov 2022, 17:21

Hell Razor5543 wrote: 21 Nov 2022, 22:30 Are you sure that is air gushing OUT? Next time it happens securely hold a length of string close to the filler cap, and see which way it moves as you open the cap.

Pretty sure it was a bit of a blow out. I can't recreate it at the min because there is only about 10 litres in tank.... I will need to top up and that causes the issue...im between a rock and a hard spot

Unread post by **Dormouse** » 22 Nov 2022, 18:50

Try running the car with the fuel cap in place but not clicked shut. Watch out for rain, spray or any water getting into the filler. Your tank should neither pressurise or have a vacuum. A very tiny hiss is possible when you open the filler cap but you should not really hear it. If you can hear a definite hiss then there is a tank issue. From my experience, given your description of symptoms, I would be looking for a blocked breather causing a vacuum in the fuel tank which will be stronger, quicker, when the tank is more full. When the tank is low, the vacuum build up takes longer.

Gazzaman22 · Unread post by **Gazzaman22** » 24 Nov 2022, 18:36

Would cutting the breather pipe and using an airline to try and clear a blockage be sensible? And then rejoin?

Unread post by **Michel** » 24 Nov 2022, 18:40

Gazzaman22 wrote: 23 Oct 2022, 20:17 Thanks Hell,

James' new name forever! Thanks Gazzaman22!

Unread post by **Dormouse** » 25 Nov 2022, 12:15

Pressurising a plastic fuel system ( tanks and pipes) is not a good idea. If you do use and air line set the line pressure low. Beware, some breathers go to a cannister which separates and feeds fumes to the inlet system. I don't have experience with this model - perhaps others can advise precisely. However, be very careful with compressed air in the fuel system lines.

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C5 cut out while driving UPDATE

C5 cut out while driving UPDATE

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