[GaKu]

Hi all,

I have a 2011 Fd 1.4 Petrol. I have noticed that when the tank is full, acceleration is quite slow compared to half a tank. I initially thought this was due to weight. However, with passengers in the car when on low fuel, the car seems to accelerate fine.
Any suggestions on what could be wrong if at all?

Wishing you all a happy new year!

[Dazzler]

Any other "symptoms " to help with the diagnosis?  Be handy if you could do a rough measure of the difference on a bit of closed or quiet road somewhere.  Just to confirm it's not an illusion. Not doubting you, but be interesting to quantify the difference. 

Can't recall that issue being mentioned before. Very interested to hear other responses.

[eye30]

Could it be fuel flow being restricted when tank full i,e. Vacuum being created due to no free room in tank so restricting flow

[GaKu]

Eye 30, I'll try to not brim it this time.
I usually pump again after it stops.

[GaKu]

I'm inclined to believe this was something to do with overfilling the tank. I read on some other websites that overfilling could cause a block in the return pipe of the fuel pump thereby reducing overall fuel injection rate.
Could this be true?

[Dazzler]

I'm inclined to believe this was something to do with overfilling the tank. I read on some other websites that overfilling could cause a block in the return pipe of the fuel pump thereby reducing overall fuel injection rate.
Could this be true?

Did NOT brimming it make a difference?

I usually don't brim a petrol, unless about to undertake a longish drive immediately to avoid the risk of heat expansion causing an overflow / leakage. Although I believe the risk of that may have been overstated.

Many of our members brim their diesels without any ill effects. 

[GaKu]

I feel so, yes.
By not brimming I mean I did not fill any more after the pump stopped the first time.
Earlier, I used to pump until it stopped a couple of times and probably this had some effect.