|
Title: Petrol Filler Cap Post by: Ammy on August 13, 2012, 02:01:47 PM When I release the screwed filler cap on the petrol tank, I always get a "hissing" sound. Not sure whether it's air coming out or going in. Comments please on whether this is normal. B.T.W I have an aluminium tank. Ammy
Title: Re: Petrol Filler Cap Post by: MattNoVAT on August 13, 2012, 03:32:08 PM Its likely that it's sucking air in when you unscrew the cap, as fuel is consumed it creates a slight vacuum inside the tank.
The hissing is it equalising. I have seen some cars with a small hole drilled in the cap to stop vacuum building up. Or you can check your fuel tank vent pipe is not blocked or kinked, I managed to compress my vent pipe and after driving 100 miles the vacuum drew the fuel back into the tank and the car didn't fancy starting for a while. Title: Re: Petrol Filler Cap Post by: droptop on August 22, 2012, 03:39:05 AM THAT'S why mine is difficult to start after a long journey, and I have the hissing!
Thanks Matt. Problem solved without even having to ask ;D Title: Re: Petrol Filler Cap Post by: Ammy on August 22, 2012, 09:09:15 AM Rather than drill the filler cap, I decided to drill a small hole in the breather hose to the filler neck and insert a piece of "washer pipe" which then follows the overflow pipe through the bottom of the rear wing. Same result.
|