Hi
I was wondering if anybody has any idea why I lose petrol from the autovac.
If I don't start my 1929 Clifton Tourer for a couple of weeks the petrol has disappeared from the autovac and is completely empty. I have placed A4 paper under autovac and pipes and carburettor and no sign of leaks.
Could petrol self syphon back to the tank, has anyone had this happen to their car.
Thanks
Paul Rumsey
May I wish all members a Happy Christmas and a safe and healthy 2023.
FUEL LOSS
Re: FUEL LOSS
Hello Paul
The design of the Autovac is such that siphoning back to the tank is simply not possible. There is a non-return valve in the petrol feed pipe, an air gap of about 2inches between the feed pipe and the petrol level in the full Autovac and an air vent in the Autovac lid which would break any vacuum so preventing siphoning.
Do you turn the petrol tap below the Autovac off?
If you leave the tap on, petrol will evaporate from the float chamber and be replaced with petrol from the Autovac. This can drain the Autovac surprisingly quickly, certainly within two weeks! You also need to be sure the tap is in good order and shutting off the supply fully.
Merry Christmas to all
Martin J Booth
Barnsley
The design of the Autovac is such that siphoning back to the tank is simply not possible. There is a non-return valve in the petrol feed pipe, an air gap of about 2inches between the feed pipe and the petrol level in the full Autovac and an air vent in the Autovac lid which would break any vacuum so preventing siphoning.
Do you turn the petrol tap below the Autovac off?
If you leave the tap on, petrol will evaporate from the float chamber and be replaced with petrol from the Autovac. This can drain the Autovac surprisingly quickly, certainly within two weeks! You also need to be sure the tap is in good order and shutting off the supply fully.
Merry Christmas to all
Martin J Booth
Barnsley
Re: FUEL LOSS
Hi Martin
Thanks for your reply.
So there is no way it could self syphon thanks for explaining that, I always turn the tap off after having been on a run and isolate the battery via a switch.
I replaced the tap last year and can not trace any leaks by placing A4 sheets of clean paper under autovac, pipe to carburettor and under carburettor.
I think I will remove tap and piping and reseal everything.
Thanks for your help.
Regards
Paul Rumsey
Have a safe and healthy 2023.
Thanks for your reply.
So there is no way it could self syphon thanks for explaining that, I always turn the tap off after having been on a run and isolate the battery via a switch.
I replaced the tap last year and can not trace any leaks by placing A4 sheets of clean paper under autovac, pipe to carburettor and under carburettor.
I think I will remove tap and piping and reseal everything.
Thanks for your help.
Regards
Paul Rumsey
Have a safe and healthy 2023.