Roll over valve and carbon canister
Discussion
I have been getting an intermittent noise coming from within the boot area, it sounds like a noisey motor/pump but after hours of trying to find it (as it only does it every now and then) I have finally tracked it down to the roll over valve. I have ordered a new valve but according to the bible this works with the carbon canister and also sorts out the ventilation of the tank.
I have (that I can see) 2 pipes coming from the tank one on the filler neck that goes to the rollover valve and one on the right direct into the tank which I guess is the return pipe.
Where do the pipes that go to the carbon canister come from? and how does the rollover valve work with the canister/ventilation.
Any help would be great so I can get my thick head around whats going on and why I am having a problem with the valve.
Chris
I have (that I can see) 2 pipes coming from the tank one on the filler neck that goes to the rollover valve and one on the right direct into the tank which I guess is the return pipe.
Where do the pipes that go to the carbon canister come from? and how does the rollover valve work with the canister/ventilation.
Any help would be great so I can get my thick head around whats going on and why I am having a problem with the valve.
Chris
On the filler side is the vent pipe and the pipe to the fuel pump (supply to engine bay). The 'wet' return from the fuel pressure reg goes to the offside part of the tank IIRC.
Even though the carbon cannister is in the offside wing, the vent pipe crosses the chassis behind the rad and runs down the outside of the nearside chassis rail (not to be confused with the pressure supply from pump/filter which is normally on the inner part of the nearside chassis rail).
Always worthwhile to make sure the vent pipe is clear and hasn't been trapped closed with tie wraps IMHO. You should be able to blow & suck through the vent easily ~ its only the purge valve side into the plenum that should have any resistance IYSWIM.
Even though the carbon cannister is in the offside wing, the vent pipe crosses the chassis behind the rad and runs down the outside of the nearside chassis rail (not to be confused with the pressure supply from pump/filter which is normally on the inner part of the nearside chassis rail).
Always worthwhile to make sure the vent pipe is clear and hasn't been trapped closed with tie wraps IMHO. You should be able to blow & suck through the vent easily ~ its only the purge valve side into the plenum that should have any resistance IYSWIM.
spend said:
On the filler side is the vent pipe and the pipe to the fuel pump (supply to engine bay). The 'wet' return from the fuel pressure reg goes to the offside part of the tank IIRC.
Even though the carbon cannister is in the offside wing, the vent pipe crosses the chassis behind the rad and runs down the outside of the nearside chassis rail (not to be confused with the pressure supply from pump/filter which is normally on the inner part of the nearside chassis rail).
Always worthwhile to make sure the vent pipe is clear and hasn't been trapped closed with tie wraps IMHO. You should be able to blow & suck through the vent easily ~ its only the purge valve side into the plenum that should have any resistance IYSWIM.
Thanks for the info I now understand how it works. I can blow through the pipe but there is some resistence. Just by turning the ignition on and off a couple of times so the pump primes it creates pressure in the tank which lasts for at least a few seconds as I have time to get out of the car go to the back and open the fuel filler cap, this then releases the pressure. I will have to see if there are any kinks in the pipe and if pressure is building up when the car is running (bit late to start revving her up now lol)Even though the carbon cannister is in the offside wing, the vent pipe crosses the chassis behind the rad and runs down the outside of the nearside chassis rail (not to be confused with the pressure supply from pump/filter which is normally on the inner part of the nearside chassis rail).
Always worthwhile to make sure the vent pipe is clear and hasn't been trapped closed with tie wraps IMHO. You should be able to blow & suck through the vent easily ~ its only the purge valve side into the plenum that should have any resistance IYSWIM.
Chris
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