Petrol cap sucking noise

[CMF_benben]

Hey, my car has had a few problems with staling when it wants. Not entirely sure what it is hopefully not the throttle body. But I was think do micra petrol tank have a breather hole because when I am filling up with petrol when I take the cap of there is a big initial suck noise coming from the tank. I was thinking maybe my petrol cap is causing a vacuum and not allowing petrol to the fuel pump/ engine. Any ideas and comments would be helpful.

BenBen

 

[CMF_evade]

MY SLX used to that..never had a problem with it though?

 

[cisco]

Yeah weird. Blue Monster gets that.. Just thought it was normal, maybe not then!

 

[CMF_Yom]

I think its just a breather valve or something. It just means the tank is totally airtight as you consume the fuel.

Which is a good thing I suppose.

 

[CMF_micragirl]

Perfectly normal, it was explained to me by Nissan that the fuel pump sits just below the filler cap on the micra, the vacuum/sucking noise is purely air that is trapped in the filler section of the tank. It's more noticeable when the tank is almost empty. If the car is stalling intermittently and or running/idling rough... it is most likely to be the throttle body/AFM.

 

[CMF_White Knight]

Thank you micragirl. Good to see that us males do not know everything and takes a lady to tell us the answer.

 

[CMF_Yom]

Does anyone have a solution for my dad's car?

You open the petrol cap and your hand is covered in petrol vapour from huge positive pressure inside the tank.

(its an aftermarket long range tank - 120L)

 

[CMF_mrh]

Is it a deisel? If so they can get messy when filling up. I know that my mate uses a Glove when he fills up his truck so his hands stay clean. This could be a similar problem because of the bigger tank. Could be a pressure release due to the deisel and the size of the tank?

 

[CMF_GTRHOLIC]

i found out tonight that the last time i filled up my skyline i forgot to put the fuel cap back on and lost it. tonight the car was boosting like crazy! would the lack of fuel cap have caused that?

 

[CMF_Yom]

If there's too much negative air pressure inside the tank and it is working against the fuel pump... mabye.

But are you sure its not just the air? Its freaking cold and moist outside at the moment!