The V8 Owners Forum -

Ian Anderson wrote:Well now

I believe there is a purge valve circuit on these systems (I know there is on on my 1990 hotwire system which I have not connected as I have other vents built in)

I believe it works on the principle that 1) engine must be at running temp and 2) revs must be above a set RPM at which time the signal opens a solenoid that vents the tank / charcoal caniister etc into the inlet tract.


This would be to stop hydrocarbons exiting to atmosphere

Ian

Ohh no, not got the luxuries of things like that, pump and regulator only,

Ian Anderson wrote:Well now

I believe there is a purge valve circuit on these systems (I know there is on on my 1990 hotwire system which I have not connected as I have other vents built in)

I believe it works on the principle that 1) engine must be at running temp and 2) revs must be above a set RPM at which time the signal opens a solenoid that vents the tank / charcoal caniister etc into the inlet tract.


This would be to stop hydrocarbons exiting to atmosphere

Ian

this is the std setup :

Dangerdoc wrote: It is easy to confuse vacuum hiss on opening the filler cap with overpressure hiss, but the cloud of petrol is a pretty good indicator. Thank goodness you were not having a fag at the time or you might have looked like the inside of a charcoal filter.

I'm fairly confident that we are all talking about pressure, not vacuum, so, er, what is your point?

The pressure was excessive, enough to spray fuel in my face,
and if the non retun valve is fubared, could theis be indicative of the pump on its way out?

Hi Paul B,

My point was perfectly clear and I cannot understand your obtuse reply.

~Yes we are, hopefully, all grown ups and the main consensus is pressure escape. The point is that with the dicussions on the fuel filler cap the noise can be mistaken as not only pressure escape but air entry.

Both my Landrover 4.0 V8 and Range Rover Classic 3.5 have noise evident on fuel filler cap release. Both are the sound of air entry not escape.

In my post, Paul, I did highlight that as there was fuel escape creating an aerosol then it was obviously pressure escape but... reflection on the other discussion points brought about alternative discussion points.

The point I was making further suggested over pressure of the fuel tank by way of vacuum entering into the fuel return system and thus pressurising the fuel tank by a remote ingress by a venturi type mechanism.

Hope this clears your confusion.

One of the benefits of this forum is that us mere minions can also make suggestions. This might not be the actual answer but does open other thoughts of cause and effect to stimulate discussion on solution - dead easy really.

Doc

Paul B wrote:

Dangerdoc wrote: It is easy to confuse vacuum hiss on opening the filler cap with overpressure hiss, but the cloud of petrol is a pretty good indicator. Thank goodness you were not having a fag at the time or you might have looked like the inside of a charcoal filter.

I'm fairly confident that we are all talking about pressure, not vacuum, so, er, what is your point?

I thought the point was lit fag(flame)+fuel vapour(from pressurised tank)=explosion