Good afternoon
My vent pipe from the tank under the rear seat has periished. I've bought a new replacement with clips etc but as the weather is so bad I've had to delay the work. In the meantime I'm only putting 15 litres in the tank at a time and to prevent fumes entering the cabin I've plugged the vent outlet from the tank. I've noticed the last 3 times of filling the tank that the fuel is flowing out of the filler neck as if shes full . could this be caused by the lack of venting and will it have a detrimental affect on starting and running
Thanks
Fuel pressure in tank
Moderator: martauto
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Brianmoooore
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Which vent pipe? If you've blocked off the vent pipe that runs to the front of the car, and your filler cap seal is good, 15 litres will be all you ever get in the tank in the future, since it will be sucked flat by the fuel pump as the fuel is used up. This happened to us once, on a brand new Ford that had been assembled incorrectly.
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Bonymaenjack
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Brian the one on the top of the tank which runs through to the offside rear arch into the boot areaBrianmoooore wrote: ↑Sat Dec 14, 2019 9:36 pmWhich vent pipe? If you've blocked off the vent pipe that runs to the front of the car, and your filler cap seal is good, 15 litres will be all you ever get in the tank in the future, since it will be sucked flat by the fuel pump as the fuel is used up. This happened to us once, on a brand new Ford that had been assembled incorrectly.
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Brianmoooore
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There's a small vent pipe from the LH side of the tank that allows the tank to fully fill, especially when the car is lower on the right hand side than the left, and there's the large pipe that is the main tank vent. No damage will occur if either of these is blocked off. There's also a small pipe from the top of the vent bottle that runs across the top of the tank. This is the one that mustn't be blocked
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Bonymaenjack
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Cheers Brian , just to confirm it is the outlet on the tank which is blocked where the 1/2 inch ? rubber, fibre clothed reinforced pipe fits and not either of the small bore hard plastic pipes .Brianmoooore wrote: ↑Sat Dec 14, 2019 10:43 pmThere's a small vent pipe from the LH side of the tank that allows the tank to fully fill, especially when the car is lower on the right hand side than the left, and there's the large pipe that is the main tank vent. No damage will occur if either of these is blocked off. There's also a small pipe from the top of the vent bottle that runs across the top of the tank. This is the one that mustn't be blocked
Thanks again
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Brianmoooore
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`No damage will happen if the big hose is blocked off, other than 'blow back' from the filler neck when filling with fuel. IIRC, the hose is an odd size (14mm?) , and difficult to replace with anything other than the genuine article.
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Bonymaenjack
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The OEM are still available , I paid about £37 for my dealer replacement . I'm just waiting a dry day to tackle it , hopefully with lesser of the issues found shown in the you tube clipBrianmoooore wrote: ↑Sun Dec 15, 2019 12:24 am`No damage will happen if the big hose is blocked off, other than 'blow back' from the filler neck when filling with fuel. IIRC, the hose is an odd size (14mm?) , and difficult to replace with anything other than the genuine article.
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Vez010
- E30 Zone Newbie

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Did you manage to sort this?
I’ve got a similar issue and am looking to get it sorted.... appreciate it if you could share your fix.
I’ve got a similar issue and am looking to get it sorted.... appreciate it if you could share your fix.
