1996 Hymer (fiat ducato 2.5td) B694 fuel tank vent? (1 Viewer)

[mrT]

Hi,we have a 1996 Hymer B694 tag axle motorhome. (fiat ducato 2.5td based) when removing the fuel filler today there was a definate vacuum going on,(loud hiss) does anyone know the location of the fuel tank vent? (i'm assuming its blocked)
thanks in advance.

 

[solaris]

There was a thread on this on Autosleepers forum. Replies seemed split between vent in cap or a breather tube. Also that a certain amount of pressure was required in the tank for fuel system to work. It’s been a bit warm too.

 

[mrT]

There was a thread on this on Autosleepers forum. Replies seemed split between vent in cap or a breather tube. Also that a certain amount of pressure was required in the tank for fuel system to work. It’s been a bit warm too.

i've looked and the cap doesnt have a vent (as far as i can see)
i dont think the tank should have vacuum........but could be the weather as you suggested.
i would have thought there should be some form of vent in the system..............
has anyone with the same vintage Hymer experienced this??

 

[Baggydave]

i've looked and the cap doesnt have a vent (as far as i can see)
i dont think the tank should have vacuum........but could be the weather as you suggested.
i would have thought there should be some form of vent in the system..............
has anyone with the same vintage Hymer experienced this??

Hi. On our last van, 2.8jtd fiat, it too always seemed to have a vacuum. We owned it for 7 years & never caused a problem. I assumed it was just how they worked?
Current van also has a slight vacuum but maybe not as much. It’s a fiat also.

 

[Sleeveless]

Are you sure the noise you hear is air rushing in to the tank and not out ? Meaning pressure is being released and not vacuum diminished . For many years now, vehicle diesel and petrol tanks haven't vented to atmosphere, instead producing a positive pressure internally by the action of the fuel return circuit, this is always more noticeable when removing the sealed filler cap when the tank has a low content (usually the case).

^{_{Subscribers  do not see these advertisements}}

 

[mrT]

Are you sure the noise you hear is air rushing in to the tank and not out ? Meaning pressure is being released and not vacuum diminished . For many years now, vehicle diesel and petrol tanks haven't vented to atmosphere, instead producing a positive pressure internally by the action of the fuel return circuit, this is always more noticeable when removing the sealed filler cap when the tank has a low content (usually the case).

yes you are probably right. curiously it hasnt done it since! anyway,it hasnt caused an issue and van runs fine. (just one of the curiositys of a new to us van!) thanks.

 

[mrT]

Hi. On our last van, 2.8jtd fiat, it too always seemed to have a vacuum. We owned it for 7 years & never caused a problem. I assumed it was just how they worked?
Current van also has a slight vacuum but maybe not as much. It’s a fiat also.

yes you are probably right. thank you.