Less Petrol = Less Power / Response

[Astro Bear]

Whenever I fill up my r33 with a full tank of fuel the car feels like it has way more power / response. Whenever the fuel starts to get below half a tank the car gets 'doughier' and keeps getting worse the lower the fuel reading is. Last night I still had a quarter of a tank and was driving like a slug, when I filled up, BANG, response is back and car feels like it has an extra couple of kw atw lol.

For the record, I have a 400hp fuel pump and am only running 170kw atw, and this problem has been happening even on the stock fuel pump before the mods.

Can anyone explain this?

Cheers,

Adz.

[GTRNUR]

You would need to prove it on a dyno and log the AFR's. What you are describing could be symptomatic of a fuel pressure problem. This could indicate issues with the fuel pump, or an issue with the charcoal canister. Is your charcoal canister still connected?

[Astro Bear]

I have no idea mate, I'm not a very mechanically minded person. I had it dynod a few weeks back when I had some work done and apparently the AFRs were all good, it's just something that I notice ,being that I drive the car on a daily basis. I imagine the charcoal canister is still connected as I got the car 100% stock and have only changed the basics.

Thank you for your reply, it is much appreciated.

[Astro Bear]

Just remember I posted in this thread a while ago:

http://www.skylinesaustralia.com/forums/R3...p;hl=filling+up

Perhaps there is some connection?

[STATUS]

is it worse on hot days?

[R31Nismoid]

sounds like poor mounting of the fuel pump or blocked fuel filters and so on

[paulr33]

yeah the amount of fuel in the tank and how much you put in wont have an effect

even running empty has no effect, as the pump sucks from the bottom all the time anyhoo

your likely causes as ash said, given you dont have the stock pump

is poor pump install - its probably floating around, and when go lower than half full, it lays on it side or something silly

check the basics

look inside the fuel tank and find the pump

it should be slotted into the hook / latch thing on the roof of the tank, so that it goes all the way to bottom and doesnt slide / move around

[neo32]

what does the charcole can do?

[lachlanw]

it vents the fuel tank into the intake manifold under vacuum