Object in Rear Wheel Arch?

[SimonKD]

While cleaning up my rear suspension componants earlier i noticed 3 items within the passenger side rear wheel arch. I take it that it's the fuel pump lowest down behind the wishbone pivot, followed by the larger fuel filter above but what's the cyliyndrical item that is larger still behind the fuel filter. It has a jubilee clip top and bottom & wires, just curious thats all?

Regards
Simon

[pmessling]

probably the charcoal canister, although only guessing

[BLUETHUNDER]

It is the carbon canister.

[SimonKD]

Thanks chaps

Am I right in thinking that as fuel is used air enters the tank via the carbon canister? Also what are the wires for atteached to the above item?

Sorry for all the questions.

Regards
Simon

[Tanguero]

The carbon canister is to stop fuel vapour escaping to the atmosphere. The object on top is a solenoid valve which opens and closes a vacuum line that runs the length of the car and up inside the engine bay to the 4 way connector which provides manifold vacuum. There is also a roll over valve behind the fuel tank in the line between the canister and tank.

[SimonKD]

Thanks for info

I've noticed when I open he filler cap to fill up I get a rush of air as I break the seal on the filler cap. This seems to be a rush of air into the tank rather than out of it. What causes this to happen, or are there several reasons for this?

Regards
Simon

[SimonKD]

SimonKD said:

Thanks for info

I've noticed when I open he filler cap to fill up I get a rush of air as I break the seal on the filler cap. This seems to be a rush of air into the tank rather than out of it. What causes this to happen, or are there several reasons for this?

Regards
Simon

Anybody?

[Gazzab]

You have to sort your carbon cannister I believe.

[SimonKD]

Gazzab said:

You have to sort your carbon cannister I believe.

So what goes wrong with these carbon cans then to cause the rush of air when opening the filler cap?

[Gazzab]

SimonKD said:

Gazzab said:

You have to sort your carbon cannister I believe.

So what goes wrong with these carbon cans then to cause the rush of air when opening the filler cap?

They stop working and so the tank can't breathe and then the tank starts to create a vacuum I think.

[Tanguero]

I think that the cannister serves 2 purposes.
Firstly the tank breathes air in through the cannister as fuel leaves.
Secondly when the solenoid valve opens the cannister is connected to manifold vacuum which presumably is to purge the vapour from the cannister.

Does anyone know under what circumstances the solenoid valve open?

[SimonKD]

Tanguero said:

I think that the cannister serves 2 purposes.
Firstly the tank breathes air in through the cannister as fuel leaves.
Secondly when the solenoid valve opens the cannister is connected to manifold vacuum which presumably is to purge the vapour from the cannister.

Does anyone know under what circumstances the solenoid valve open?

This makes sense but I don't know if it's right.


When the vehicle is shut off, there is a pressure imbalance within the fuel tank caused by fuel being siphoned out, but no air being let back in to take up the empty space. The lower pressure in the gas tank promotes a greater rate of evaporation, letting some of the fuel become a gas. Eventually the tank's internal pressure equalizes, at which point the gas leaves the tank through the vent port and goes into the carbon canister. It's trapped there by the properties of the carbon within the canister, keeping it from escaping into the air. When the vehicle's engine starts, the sudden suction created along the intake manifold opens up the purge valve and pulls all the gaseous fuel out of the canister and burns it in the engine. The canister goes unused until the car is turned off again.

Read more: How Does a Carbon Canister Work? | eHow.com http://www.ehow.com/how-does_5047404_carbon-canist...

Regards
Simon

[Tanguero]

Air has to be getting into the tank to replace the petrol while the engine is running or the tank will collapse. In practice the vacuum will starve the engine of fuel despite the pump after about five minutes of running. I know this from experience when I had a faulty rollover valve that completely blocked the line to the carbon canister.

There is an electrical connection to the valve on the carbon canister which opens and closes it it. I am not sure when though.

[GT6k]

Just for info, the tank and valve are from a Rover 25, I picked up a spare one from my local scrappy recently.

The rollover valve appears to be a one way valve but with a restriction in both directions. I think the aim is to run the tank at negative pressure so vapour only ever goes out via the cannister.

[SimonKD]

GT6k said:

Just for info, the tank and valve are from a Rover 25, I picked up a spare one from my local scrappy recently.

The rollover valve appears to be a one way valve but with a restriction in both directions. I think the aim is to run the tank at negative pressure so vapour only ever goes out via the cannister.

Am I right in thinking that the rollover valve only closes in the event of the vehicle ending up on its roof to stop fuel flowing from the tank?

Regards
Simon

[mikesr]

Here is a linky to my findings from a few years ago
(Have I really had a Cerbera that long!)