Which (other) O-rings to replace on W202 C250TD fuel system?

[hobbsy]

I've replaced all the clear plastic pipes (inc o-rings, the complete pipes come with new rings fitted) between the fuel filter housing and the fuel pump.

Which other o-rings are there that I've missed.

I found a thread a while ago when searching on this subject where he replaced all the plastic pipes (like I did) but still suffering from air in the fuel (like I *think* I am on occasions - though it is a lot better).

However I've tried searching and can't find the thread again.

Any help appreciated!

I'm also considering fitting a ball pump to help prime the system (when needed, i.e. fuel filter change - still a problem even if you fill the filter). This would be taken off a peugeot / citroen.

Anyone know if this contains a check valve (one-way valve) or if would be a good idea to fit one.

I think one of the main problems is that the fuel drains back into the tank a bit over night (especially if parked on a slope) and as the first pump (lift pump) is in the engine bay you have to crank it for ages to displace the air.

A check valve would stop this drain back.

And a ball pump would make it possible to bleed air out with cranking for ages.

 

[Dieselman]

If all the pipes are sealed properly there is no need for an additional pump. The leak could be either on the fuel supply side or leak-off return.

Check where the leak is by revving the engine hard from idle whilst watching the pipes for bubbles.

Wherever you see bubbles first is where the leak is.

There is an O ring inside the fuel shut off valve bolted onto the pump body, which can leak.