Fuel Pump

[Stoney_god]

When I turn the ignition on should I be able to hear the fuel pump buzzing ??

[325sportcab]

Yeah you should hear. the fuel pump is under the rear seat base on the drivers side. there is a black cover over the top of it held in with 4self tapin screws remove that and the pump is there. if you turn on the ignition and you cant hear it with the seat and cover removed then its not working.
there are 2 connectors on the pump. The small one is power supply and the big one is for the on-board computer. if your pump is broken then its going to cost you Ԛ£125 for a new one from euro-parts as i brought one just the otherday.
Hope this helps.

[Stoney_god]

The car hasn't been started for 18 months. Charged battery up and it fired first time. Ran for about 5 sec spluttering away then conked out. It sounded like it was being starved of fuel and I couldn't hear the pump buzzing away so I reckon that is the problem.

[smithy318i]

Not all fuel pumps 'buzz' Some are louder than others. If your fuel pump is working properly, there should be an absolute TORRENT of fuel going through the pipes.
I advise you to connect the pump directly to 12 volts to see if it works before handing over 125 notes.

It could be the wire link under the glovebox, or the relay, or even just a fuse.

[A1BMW325iSport]

Not all fuel pumps 'buzz' Some are louder than others. If your fuel pump is working properly, there should be an absolute TORRENT of fuel going through the pipes.
I advise you to connect the pump directly to 12 volts to see if it works before handing over 125 notes.

It could be the wire link under the glovebox, or the relay, or even just a fuse.

link wire?

[smithy318i]

The green wire that plugs into the OBC relay box.

[irish320i]

you could cross the terminals under the relay could just be a stuck relay not sure of the terminals to cross but its not to hard to find out

[johnono]

are there any obvious tell tale symptoms of a failing fuel pump (apart from the super obvious " it wont start u arse!" )

[reggid]

my fuel pump (a new one) does not work at all when the ignition is on. it only works (and works well) when the car is being started (cranking) or when it is running. I think this is causing me starting troubles ie multiple cranks required. There is no voltage getting to the terminals when the ignition is on hence it doesn't run when the ignition is on. Does anyone know what can cause this. My thoughts are that there is no voltage getting to the pump when the ignition is on because of the computer being faulty (i have checked relays and done tests from th bentley manual which indicate this).

[karlp]

My understanding is that the fuel pump ONLY works when the engine is turning over. This would ensure then the engine stops the fuel is not pumping (safety feature).

When starting the pump will receive a signal from the ECU and will supply sufficient fuel to start the car.

Karl

[astondg]

My understanding is that the fuel pump ONLY works when the engine is turning over. This would ensure then the engine stops the fuel is not pumping (safety feature).

When starting the pump will receive a signal from the ECU and will supply sufficient fuel to start the car.

I think that's why they have the kill switches in race cars, to stop the fuel pump and other stuff?

Mine runs when the ignition is on and not just when starting the car. Mine ran all night once because a relay (I think) got wet, the mechanic that fixed it said the petrol goes to the engine and then isn't used so it goes back through the return pipe to the petrol tank?

Aston

[reggid]

My understanding is that the fuel pump ONLY works when the engine is turning over. This would ensure then the engine stops the fuel is not pumping (safety feature).

When starting the pump will receive a signal from the ECU and will supply sufficient fuel to start the car.

Karl

the manual seems to say that it will run for a few seconds when ignition is on then it will go off for the reason you gave. I'm not 100% sure as mine does not run and would like to hear from anyone who owns a 325i(s) or 525i to see if it is the case

[A1BMW325iSport]

when you turn the ignition to stage 2 the pump should buz for a split second, and then when you crank the engine the relay will kick and and run the pump till you turn the ignition off