Starting and stalling woes...W210320CDI

[bigtwin]

Following on from this: http://forums.mercedesclub.org.uk/showthread.php?t=21304&highlight=stall

In a nutshell, starts runs for about 10 secs then stalls, then requires large amount of cranking to get going again.

I have replaced the engine side fuel lines (3) and this hasn't helped. Have been looking at the fuel flow (now that I can see through the new pipes), and need some info.

1. How "smooth" should the fuel flow be out of the filter tub? Should it be pure fuel, or is some turbulence/bubbles the norm?

2. It seems that by the time the fuel gets up to the top pipe en route to the injectors, all is well and it's nice smooth fuel, regardless of 1. above. Thus, it has to be a vacuum causing the flow to stop and cause the stalling - right?

3. If 2 above is correct, is it also correct to say that this can only be the result of air ingress somewhere the engine side of the filter pot reservoir?

Tks all

 

[television]

You must not have any bubbles in the system, the reason being that air compresses and fuel does not, air can come from the return to tank part of the car and that needs to be checked

 

[bigtwin]

You must not have any bubbles in the system, the reason being that air compresses and fuel does not, air can come from the return to tank part of the car and that needs to be checked

Thanks. Should the system self-purge once air has got in (i.e. when changing the fuel lines) - if not, how do you bleed it (there being no manual primer on the fuel system AFAIK?

Been out with a torch and done some more fettling!

1. There is definitely a small stream of bubbles coming out of the filter pot into the fuel line.

2. Worsens when cap is loosened, but doesn't stop when tightened. Can see no damage etc to seal/pot.

3. Once switched off, a bubble of air about a cm long remains at the top of the fuel line where it exits the filter pot.

I am assuming that none of the above is right and proper - and that the air could be getting in anywhere between the tank and the filter?

 

[television]

I believe the way is to slacken the pipes at the injectors so that its pumped out

If I am wrong someone will soon say so

 

[bigtwin]

Further perplexing observations.

1. On start up, for the first 2 secs it runs smooth and air free out of the filter pot. Then, goes bubbly again.

2. Swapped out the rubber feed pipe from the hard pipe at the bulkhead to the filter - makes no difference.

3. Checked and re-seated the seal on the filter pot - all seems fine - makes no difference.

4. I note that there is a valve of some sort on the return from engine side (small spring in housing in filter cap) - could this be stuck - seems to be a pin hole on the top of the cap where the two pipes go in?

 

[hmang]

is there any dampness around the fuel pump on the front end of the engine ?

my s 320 cdi had this and needed a seal kit fitting.

got the seals from P B ASHER bosch diesel place in southampton

 

[bigtwin]

is there any dampness around the fuel pump on the front end of the engine ?

my s 320 cdi had this and needed a seal kit fitting.

got the seals from P B ASHER bosch diesel place in southampton

Doesn't seem to be, and doesn't seem that there is air getting in there, as fuel is air free, when running, coming out of there to the injection rail?

 

[bigtwin]

Resolution.

Well, after all that, and replacing the fuel lines to no avail, today I cured the problem.

Fuel filter. The actual filter, not the sealing ring at the top of the pot.

Changed it - totally smooth bubble free fuel. Doubted it, so changed it back - problems again, and so again in reverse.

"Go figure" as they say across the pond....

 

[Rideaday]

Come on back bigtwin, UKGSER needs you!
http://www.ukgser.com/forums/showthread.php?t=128777

 

[dieselman]

Well, after all that, and replacing the fuel lines to no avail, today I cured the problem.

Fuel filter. The actual filter, not the sealing ring at the top of the pot.

Changed it - totally smooth bubble free fuel. Doubted it, so changed it back - problems again, and so again in reverse.

"Go figure" as they say across the pond....

Before reading this post I was going to say 'blocked filter'.

It causes the pump to suck harder and sucks air in past the joints.

 

[bigtwin]

Before reading this post I was going to say 'blocked filter'.

It causes the pump to suck harder and sucks air in past the joints.

Guess that makes sense when you thing about it. Didn't look particularly grubby, and it was well off from a scheduled change at service, but I guess that must have been it.:idea: