vmax

This might sound strange... but i have noticed that after I have filled up my tank the performance goes up by quite a percentage.

I normally run the car until the fuel light comes on.. then fill it up.

After a fill up the car seems so much more eager. ( MY01 running on SUL)

Does the ecu go into economy mode when fuel goes low. It happens every time.. I'm sure it's not me

RON

It probably goes better cos your wallets lighter!

stick

From what I've heard (pinch of salt and all that) fuel will loose octane if you leave it for a while. How long does it take you before you have to fill up?

Apparently it is also best to fill up the tank if you're not going to be driving for a while. Less air in the tank; reduce the loss.

vmax

RON,

Tell me about it... But if I wanted economy I would have bought a focus diesel or something

Any way I don't smoke.... I let the scooby burn my *** money instead, it just happens to smoke a lot of ****.

Stick,

Must admit never heard that before... If that is true.. You really need to fill up at a busy petrol station where the fuel is quickly replenished.

My fuel lasts just over a week at 300 miles if I'm a good boy. under a week at 220 if I'm a bad boy

Steve vRS

Could be bull**** but here goes.

All pumps require a pressure on their suction side to work. If the scoob's fuel pump is a centrifugal type, the greater the pressure on the suction side, the higher pressure and flow it will deliver to the engine.

When the tank is full, the head pressure on the fuel pump is greater and so the pressure and flow to the engine is greater, therefore more performance.

This theory may be bullsh!t for engines, but it works on chemical plants .

Steve

Adam M

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Richiehash:
<B>does the car suck in air when you fill up if so you may have a blocked breather. vacuum in the tank makes it harder to pull fuel from it.[/quote]

when I am near empty my car always sucks in with the fuel tank open. I thought the tank was pressurised and this is gas escaping?

Am I completely wrong? and if so, ould this blockage explain why my car has had problems idling?

nitro

Stick
You are absolutely correct in what you say loosing octane.
Temperature also has a lot to do with octane loss but wouldn't think you have the excessive heat problem.

Richiehash

does the car suck in air when you fill up if so you may have a blocked breather. vacuum in the tank makes it harder to pull fuel from it.

Richiehash

when it plays up at idle try running with the cap off as i think the breather is in it if the idle clears up this could be it.if you try to drive like this take it real slow on corners. richie

scoobs

IMHO the phenomenon of the empty tank slow car, full tank fast car, is due to the driver unconsciously driving slower when there is little fuel in the tank.

I know with all the cars I have owned that they seemed to be slower when I was running low on fuel, but as soon as I filled up there would be a marked improvement in performance. Basically I think I just naturally drove the car harder when I knew there is a lot of fuel in the tank.

Of course this may be a load of cr*p!!!

Scoobs

John 555

Could it be a weak fuel pump, so when the tank is full the pressure is greater ?

WREXY

My car, a MYOO Turbo goes better and better as the fuel level goes lower. I'd say due to the weight going lower and lower.

Steve vRS

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by John 555:
<B>Could it be a weak fuel pump, so when the tank is full the pressure is greater ?[/quote]

See my post above. It's the increase in NPSH (Net Positive Suction Head) that does it!

Steve