non starter - electrical

Sat Jul 16, 2005 3:38 pm

Hi guys, hoping someone can help. Car wasn't starting and assumed it was a faulty fuel pump. Fitted second hand pump - still not starting. After some investigation I'm not getting a supply to the 2 pin plug for the pump (green wire with purple stripe and a brown wire) I'm now thinking fuel injection relay faulty. Where is this located ? Car is H Plate 325i.

Sat Jul 16, 2005 4:20 pm

Fuel pump relay is in the engine bay on the scuttle panel. You may have to remove some padding from the bulkhead wall. There may be three relays.

When you turn ignition on you should hear a click if the relay is working BUT one of the relays next to it is the load reduction relay which will click when you turn key to start car.

If the pump relay does not click then check fuse box.

Brown wire is earth

Karl

Sat Jul 16, 2005 4:35 pm

Cheers for that bud. Still no joy though. Fuse no. 11 is for the pump - it's fine. Swapped relay for one I def know is working - still no supply on green/purple wire when turning over engine.

Sat Jul 16, 2005 4:59 pm

is the ignition switch giving a live to the relay on stage3 ?

if it isn`t the relay won`t kick and enable the fuel pump

Sat Jul 16, 2005 5:01 pm

Check the following with a meter.

Does power get to the relay to activate - measure all pins to ground (voltage).

If no power check fuses 9 , 11, 21

If power then relay should click - if it does check green /violet cable to ground (ignition on).

Karl

Sat Jul 16, 2005 5:05 pm

Thanks for that guys - will check in a wee while - dinner is on the table.

Sat Jul 16, 2005 6:37 pm

Right guys my findings are as follows :- On ignition pos 2 relay is getting 12v to red wire, 12v to red/white, 12v to brown/green 0v green/purple. On ignition position 3 above wires are getting 12v but still sweet F.A. on green/purple. Relay not clicky clicky either.

Sat Jul 16, 2005 7:37 pm

Right

the relay is not being switched as there is no click. So as you have power to all the other terminals it can only be that the ECU is not giving a signal on the remaining cable (brown/?).

Can you try another ECU?

Karl

Sat Jul 16, 2005 10:00 pm

Why don't you short across pins 30 and 87 of the fuel pump relay socket, so that the fuel pump is powered continuously, and check that the engine runs?

Sun Jul 17, 2005 1:02 am

the problem is either the ignition switch or wire coming from it, or maybe the ecu

Sun Jul 17, 2005 1:06 am

take a wire from stage3 ignition to the fuel pump relay,

i had this problem a few years ago on my 320i

when trying to start the car the relay wasn`t getting a live from ignition stage3

but the car would run with the fuel pump bridged

so i took a new wire from the ign. switch to the fuel pump relay and it
all worked fine then, the original wire must have broken down

Sun Jul 17, 2005 6:58 am

err

If you read above he has power so no point running a separate lead from ignition to pump.
The problem is the ECU is not activating the brown/? wire. Iwould earth the brown/? wire from the relay this should start the pump BUT if you have other problems in the ECU it will not start.

Karl

Sun Jul 17, 2005 8:25 am

Taylor325i wrote:Right guys my findings are as follows :- On ignition pos 2 relay is getting 12v to red wire, 12v to red/white, 12v to brown/green 0v green/purple. On ignition position 3 above wires are getting 12v but still sweet F.A. on green/purple. Relay not clicky clicky either.

Taylor,

The reason the fuel pump relay is not energising, is because the ECU is not asking it to. You have the correct 12v on the red & red/white wires. Your problem is that you DO have 12v on the brown/green wire.

When the ECU wants the pump to run, it will pull the brown/green wire to 0v (GND), and the relay will energise. I would do as Brian suggested and short pins 30 & 78 and see if the car runs. If it runs like this, then you may well have an ECU fault. If it doesn't run (which is more likely), then your problem is further back.

Have you checked to see if the main Motronic relay (the one next to the fuel pump relay - usually white) is clicking ?

Another fairly common problem that can give these symptoms (pump not running), is a problem with the crank sensor. I have seen these horribly gunged up with oil, and not sending the correct pulses to the ECU. If the ECU doesn't think the engine is rotating, it will not energise the pump. Try pulling the sensor and giving it a good clean with some brake cleaner.

Ian.

Sun Jul 17, 2005 9:22 am

A1BMW325iSport wrote:take a wire from stage3 ignition to the fuel pump relay
so i took a new wire from the ign. switch to the fuel pump relay and it
all worked fine then, the original wire must have broken down

This wire doesn't exist in the first place.
If you ever want this car to run again, follow Ian332isport's instructions exactly.

Sun Jul 17, 2005 2:18 pm

Crank sensor was filthy - Ian you da man!!! Cheers matey.
Thanks to every one else for your input - much appreciated.

Cheers Guys.

Taylor.

Sun Jul 17, 2005 2:21 pm

P.S. Spare fuel pump for sale !!!!!

Sun Jul 17, 2005 2:23 pm

Taylor325i wrote:

Crank sensor was filthy - Ian you da man!!! Cheers matey.
Thanks to every one else for your input - much appreciated.

Cheers Guys.

Taylor.

Mon Jul 18, 2005 1:52 pm

Sorry I am late but I wanted to say same happened to me: the crank sensor!

Wed Nov 16, 2005 8:50 am

Chaps, I think I've got a similar prob with my non-starting 318iS.

It turns over fine but wont fire up. The fuel pump isnÃƒ”š't starting (you canÃƒ”š't hear it prime when you turn the key) so I suspect the Crank Sensor fault as the fuel pump relay is working fine and the fuel pump runs when I apply 12v directly to it.
The starter motor was changed recently (by a garage who thought they had all the answers..) and IÃƒ”š'm hoping they disturbed something that can be easily fixed.
Question is: Where is the crank sensor on the M42 engine?
And, how can I check it out?

Cheers..