325i fuelling query....

Tue Jun 01, 2010 11:31 am

Just a quick one, I'm getting no voltage to the fuel pump when turning the car over. I've read my manual and it says to bridge 2 connections in the port where the fuel pump relay lives. I've done that and I've tested that the pump is working as it should, and it is.

So I've tested if there's voltage going to where the fuel pump relays plugs on, but there's no voltage. I've also tested the relay and that's working fine. I have also checked the fuse in the fuse box and that's fine.

Checked if there's any voltage at the pump itself and there isn't any.

Has anybody had the same symptoms, or any ideas as to wat this could be without having to chase all the wires from the relay terminal? Any replies much appreciated. Matt

Thu Jun 03, 2010 9:37 am

Any1?

Thu Jun 03, 2010 3:36 pm

Will, I've checked that and there no feed going to the fuel pump relay point. Any other ideas

Thu Jun 03, 2010 9:17 pm

I had the same problem and it was an inline 50amp fuse that came from the battery. It was in the boot, i had to remove a few bits of trim to find it. Seems to give power to the ecu and fuel pump relay.

hope that helps.
Matt

Thu Jun 03, 2010 11:20 pm

If this is a 325i saloon, with a battery mounted in the boot, take the cover off of the phantom battery terminal on the engine bulkhead, just behind the front battery tray, and check for power (with a bulb, not a meter) at the smaller terminal.
The feed to this terminal comes from the battery, via a fusible link in the smaller cable near the battery.
(P.S. As matt has already posted while I've been typing this!)

Fri Jun 04, 2010 2:26 pm

Where's the inline fuse located if my battery is in the engine bay? Which lead off the battery terminal do I need to follow to source this inline fuse?

Thanks for all the replies

Fri Jun 04, 2010 7:15 pm

If your battery is in the engine bay, there is no inline fuse.
The red wire to pin 30 of your fuel pump relay (pin 30) connects directly to one of the smaller red wires that connect to the battery + terminal. If there's definitely no power on pin 30, check out these connections.

Fri Jun 04, 2010 9:46 pm

Just checked brian and I hav a constant live feed of around 12volts to pin 30 on the fuel pump relay.

Any other ideas?

Fri Jun 04, 2010 11:35 pm

We haven't asked whether or not the plugs are sparking when the engine turns over. Do they?

Sat Jun 05, 2010 3:22 pm

Will and brian, I'm at work nw but will check both the relay and the plugs when I get home.

I will update when I can. Cheers, matt

Sat Jun 05, 2010 6:31 pm

Just checked and I hav 12 volts going to the red/White wire on the fuel pump relay, but I hav NO spark.

Sat Jun 05, 2010 7:11 pm

The fuel pump relay is only switched on by the ECU when it sees pulses from the crank position sensor. These same pulses are also used by the ECU to produce the sparks, so the chances are either the ECU is faulty, the ECU isn't getting one of its power feeds, or the crank position sensor is faulty.
By far the most likely of these is that the pulse sensor has failed.

Sat Jun 05, 2010 8:02 pm

I had this problem... its behind the toothed wheel on the front of the engine (crank postion sensor) and if it rubs on this i assume it shorts out and confuses the ecu... i just moved mine and tie wrappedit away from the toothed wheel..... job jobbed

Andy

Sat Jun 05, 2010 9:53 pm

willnz wrote:Get you hands on a multimeter, remove the large plug from the ECU, and measure the resistance between pins 47 and 48. You should read around 550 ohms.

Just done this Will and theres no Ohms between pins 47+48.

Just to confirm i shud be checking the resistance between the pins on the plug for the ECU, and not the ECU itself yh?

Ive checked it both with the ignition on and off.