Ignition not energising ECU

[jimbom30cab]

Hi

i have put an m30 lump in the 318i cab

the fuel pump will not run when the ignition is on

bridging the fuel pump relay makes it work no problem so i guessed the fuel pump relay is not being energised from the DME relay.

i checked the 2 pins of the DME relay 30 and 86 are connected directly to the battery and they are both HOT

Pin 85 of the DME seems to energise pin 36 at the ECU as this is HOT

BUT ...when i turn the ignition on the ECU harness pin 26 does NOT receive 12v.

If i bridge the DME relay by connecting pin 30 to both pins 87 then turn the ignition on there is power to the fuel pump relay across pin 86 and 85

so not really sure here

firstly it doesn't appear that the ECU is being energised

could this also be the reason why the fuel pump relay doesn't seem to be energising.

[Brianmoooore]

Safety car in the GP, so I'm not really reading this carefully, but the fuel pump relay only cuts in when the crank is turning, not when the ignition is on.

[Grrrmachine]

As Brian asks, is this when you've just turned the key to IGN ON, or when you're actually cranking the motor? If just IGN ON then no, you shouldn't get the fuel pump energised. If it's cranking and there's no fuel pump running then it may be that the CPS isn't plugged in correctly, or even working. To confirm, check that you've got a spark when cranking as CPS issues will prevent both fuel and spark.

[jimbom30cab]

ok thanks guys will do

[jimbom30cab]

The Wiki says this:


Operation

Two pins of the DME relay, 30 and 86, are connected directly to the Battery through an unfused red wire and are therefore hot (constant 12V) at all times.

Pin 85 is connected to the ECU; usually pin 36. When the ignition is turned on, the ECU receives 12V at pin 26. It will then switch pin 36 to ground which will activate the DME relay.

When the relay activates, it will connect pin 30 to both pins 87, supplying live power to the Fuel pump relay, the injectors, the ABS if fitted, and back to the ECU at pin 37.

This bit is not happening:

When the ignition is turned on, the ECU receives 12V at pin 26

[jimbom30cab]

UPDATE

Right, i bridged the DME relay and ..she started

First time in 18 months and after a full re-build it started immediately i turned the key.. SO HAPPY

do you think the relay its self is duff?

[Grrrmachine]

As far as I recall, there's nothing in the Wiki about troubleshooting an M30 engine so be careful about checking ECU pins and suchlike.

You still haven't told us whether this is happening with IGN ON or when cranking. A simple test of the DME relay is to check that the ICV is buzzing with IGN on. For more info, check out this:

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

[jimbom30cab]

Ok I replaced the main relay and she now starts

Not sure to be honest if the fuel pump is working as I turned it off after a couple of seconds as I have no coolant in yet. I Guess the fuel being pressurised might have been enough to start her

[Brianmoooore]

supplying live power to the Fuel pump relay,

Supplies live power to it, in readiness to be turned on by the ECU earthing the other side of the relay coil when it receives CPS pulses, NOT supplies live power turning it on directly.

[jimbom30cab]

Right o thanks Brian