2005 CLK 270 Cdi fuel issues

[Ukwide]

Hi all, can you help. I have a low mileage CLK 270 Cdi with fsh. Had the car serviced about 3 months ago and having used the car for work (125 mile round trip) it wouldn't start, but eventually the RAC got it going. A week later same thing, but this time wouldn't start and the garage found air in the fuel pipes, so replaced the fuel lines. A week later having used the car again for work same happened, air in the fuel lines. All joints are tight but air still seems to be getting in.

I have an E class 280 Cdi for work normally but love driving the clk , help please.

 

[Ukwide]

Well the garage have replaced all the fuel lines, new fuel filter and bled the system, and still air is getting into the fuel lines, any help would be appreciated, thanks...

 

[Ukwide]

Oh by the way, there are no fault codes coming up.......help please....

 

[PobodY]

Do the new lines have any kind of seals (for example O-rings) in them? - Any chance that one of them is pinched, so the union is tight... but not sealing?

Any idea which end it's getting in at; the fuel tank or up in the engine bay?

 

[Ukwide]

Pobody, It seems to be getting in at the tank end. The new lines all had new o rings fitted but it could be one is pinched, I'll get them to recheck..

 

[mersum1es]

Do you have at least 1/4 tank of fuel (search saddle tank syndrome)?

Fuel cooler checked?

 

[Ukwide]

Yes it's almost full, thought of the saddle tank issue, but it's almost full mate....

 

[PobodY]

Problem with the pump at the tank end?

 

[Ukwide]

Pobody, that's the next step to check the low pressure pump in the tank..

 

[Ukwide]

Hi Pobody, STAR is indicating the low pressure pump is the issue, so it's being changed for a new tomorrow, thanks for your help mate.

 

[PobodY]

It's a shame that you've had all those other pieces replaced if it's the pump in the tank that's the problem.

 

[Ukwide]

It's a shame that you've had all those other pieces replaced if it's the pump in the tank that's the problem.

Hi mate, well that didn't work out as planned, filled the car up and having used 1/4 of a tank, yet again air in the fuel pipes............ this is getting boring now......

 

[estate-agent]

Is this at any time or just first start up in the mornings (i.e stone cold)?


.

 

[Ukwide]

Hi mate it only seems to happen after about 400 miles, it doesn't matter whether it's hot or cold. I keep the tank topped up (full) but have now noticed it seems to happen when the tank drops to 3/4s full.
Logic says it's got to be something in the fuel tank, we've changed the fuel filter and fuel lines from the tank to the filter and from the filter to the engine.
When it's running it runs perfectly, in fact it's bloody marvellous, then air gets into the fuel lines and engine stops.......

 

[estate-agent]

That's a little unusual, most air leaks into fuel system seem to take a fair while to cause issues (hence I asked if it is only cold / morning start ups). I know one of the fuel filter's pipe retaining clips are renowned for breaking and many cars are no doubt driving around with these broken as it doesn't often cause a problem, worth checking the clip though as if it's broken it could be allowing air in to system. Pic of clip attached.

 

[Ukwide]

That's a little unusual, most air leaks into fuel system seem to take a fair while to cause issues (hence I asked if it is only cold / morning start ups). I know one of the fuel filter's pipe retaining clips are renowned for breaking and many cars are no doubt driving around with these broken as it doesn't often cause a problem, worth checking the clip though as if it's broken it could be allowing air in to system. Pic of clip attached.

I've checked the clip and it's fine, no problems. I am confused about fuel pumps someone has said there's two in the tank one to pump fuel from right side of tank to left side and one in the left side pumping fuel forward, but someone has said it's only one pump in the left side of the tank with a pipe running from the right side if the tank to the pump on the left side - the fuel tank is horseshoe shaped over the drive shaft allegedly, could it be the pipe is detached?

 

[PobodY]

I would have thought it's two pumps, but one in the tank (low pressure) and one in the engine bay (high pressure).

If we assume it's a problem at the tank end, does the pick-up on the pump reach the bottom of the tank? I don't know what the set up is, but often there's a "sock" of similar on the end; if that was missing, then it might make sense that the pump pulls in air as soon as the fuel level drops enough. - It's an idea anyway.

 

[Ukwide]

I would have thought it's two pumps, but one in the tank (low pressure) and one in the engine bay (high pressure).

If we assume it's a problem at the tank end, does the pick-up on the pump reach the bottom of the tank? I don't know what the set up is, but often there's a "sock" of similar on the end; if that was missing, then it might make sense that the pump pulls in air as soon as the fuel level drops enough. - It's an idea anyway.

Hi PobodY, not sure but it seems to be once the fuel level drops below 3/4s full. I know the tank is horseshoe shaped, so the fuel has to get from one side to the other, when the level drops below. The curve of the tank, maybe the pipe that draws the fuel from one side to the other has become detached and that's where the air is drawn in, but hey, I have no mechanical background lol.

 

[Ukwide]

Hi all, sorry Been busy with work, but thought you might like to know the cause of the fuelling problem.

The mechanic opened the fuel tank inspection hatch and found a small beige/brown flat circular piece of rubber about the size of a penny with a nodule in the centre on one side. This was being sucked up by the fuel pump pipe and blocking off the fuel flow..... costly but al fixed and the car is running as sweet as a nut. Cheers all and happy motoring.

Gary

 

[PobodY]

D'oh! - Good to hear it's fixed though.