why do i still get rubbish MPG?

[neilgolfboy]

just been for a good thrash around some bendy roads and then to fill up. the tank was completly dry so that dont appear to be leaking, and when i took the filler cap off, there was no sound of air rushing in, so that means the breather is ok dont it?

could a kackered fuel pump or fuelaccumulator cause crap mpg?

[jezza16v]

The fuel reservoir/accumulator acts as a pressure regulator and returns any xs fuel back to the tank. I think there is a spring loaded mechanism in it which can become seized. If it does you get the full unregulated pump pressure to the carb which can flood it and it makes the car stink! To check the accumulator, with the engine stopped disconnect the fuel tank return pipe from the top (its normally blue) and connect a short bit of fuel pipe to the free outlet and feed it into a clean bucket or bowl or something. Get someone to hold it steady for you or you'll be in a real mess. Start the engine (for a very short time) and you should get fuel pumping out of the accumulator into the bowl, this is th xs fuel the carb does not need. If you get nothing or just a very small dribble then the accumulator is b*gg*r*d. 

[neilgolfboy]

thanks for the advice mate. i will check it asap.

[T_J_G]

would this account for over-running when turning off...?

[jezza16v]

No.   Assuming you still have a Pierberg 2E2 carb, if the engine over-runs when you switch it off it probably means that the vacuum throttle shut off on the 3-4 point unit or the idle over-run control valve is not working. The over-run control valve I believe is electrically powered and controls the 3-4 point unit. It could be one or the other. There are other things that make it worse but I sha'nt bore you with them... just yet.....