Changing fuel filter

[Marneus]

Hi all,
I'm going to be changing the fuel filter on my 320 in the morning and just wanted to know how difficult a job it is? In the Haynes manual it says to depressurise the fuel system but doesn't say how to go about depressurising it. Is this necessary or is there another way to do it?
I've never done a fuel filter so apologise if this has been asked before.
Cheers
Jamie

[Brianmoooore]

To depressurise: Start and run the engine as normal, open the fuse box and pull out fuse #11. After a few seconds the engine will stall. Switch off the ignition, replace fuse #11, ensuring that it is a brown 7.5A one and not a blue 15A, unless your 320 is an ancient one.

You will still have some fuel escape, but it won't be at a pressure of 45 PSI any more.

[daimlerman]

With the engine running,pull fuse 11,this will disable the fuel pump.

Take care to fit the new filter the correct way round,it should have an arrow on it to show flow direction.Have a container handy to catch any spills.(if you use the washing up bowl,try not to get caught! )

[Marneus]

Thanks guys.
When I re start the car does the system re pressurise itself?

[TriggerFish]

Sorry to hijack a bit, but is it safe to assume the pressure would fade over time?

Mine's not been started for about two months or so - would it still need de-pressurising?

Edit - actually, thinking about it, I've removed the fuel rail, so the fuel system isn't closed any more, so I guess it can't be pressurised. (There was no pressure in the fuel rail either, so I guess I've answered my own question twice!)

[daimlerman]

Thanks guys.
When I re start the car does the system re pressurise itself?

Yes.

[Marneus]

Thanks guys.
When I re start the car does the system re pressurise itself?

Yes.

Cheers buddy

[Marneus]

Fuse 11 is a blue 15amp fuse.... It's a 1990 320, should this be a 7.5?

[BenHar]

Ben

[Brianmoooore]

should this be a 7.5?

Definitely! As stated in the handbook that came with your car.
Very early cars, with two fuel pumps used a 15A fuse, but finding one in a later car indicates a previous history of fuel pump trouble in my experience. The current that flows with a stalled (jammed) fuel pump is not sufficient to blow a 15A fuse, so the circuit is effectively unprotected.

[Marneus]

Thanks for the help. I don't have a handbook with it do can't check that.
It's had a new pump put in it recently by the previous owner do I'll try a 7.5amp fuse in it tomorrow & see what happens.