3.9 v8 14cux ecu

Hi, does anyone have any info on the 14cux ecu, got problems where i have no injector out puts, fuel pump relay powered all the time with ignition on and no out put to main relay at all,ive got inputs from coil to give injector pulse. If i connect coil out put to injectors they fire, tried ecu off a running car and same faults, all earths are ok, thanks phil

poloracer877 said:

Hi, does anyone have any info on the 14cux ecu, got problems where i have no injector out puts, fuel pump relay powered all the time with ignition on and no out put to main relay at all,ive got inputs from coil to give injector pulse. If i connect coil out put to injectors they fire, tried ecu off a running car and same faults, all earths are ok, thanks phil

Click to expand...

Struggling a bit with your description. Sounds like you've not wired the permanent live perhaps as the ECU should just prime pump. Is this a retrofit?

Better to post in the v8 section

Hi, its a standard disco it was running fine, came to it one morning and it wouldn't start, ive got good spark, but the injectors dont fire, been through fuses, wiring, immobiliser, can not find whats wrong, thanks phil

Check the inertia, are you 100% sure you have the pulse off the coil as there isn't a lot of things on the 14cux to stop injector sequence when you say it fires on injectors what do you mean? What's fuel pressure like and quality of fuel I had to swap my injectors because bad fuel lines filled them whither craps.

Did you swap out the main and fuel pump relays under driver's seat?

It's a long shot, (based on the 300 series V8 disco) but as the ECU has only one connection to signal the ECU on when to open the injectors and that's from the coil terminal on the white/black wire, so therefore check that this is a good connection also check that both resistors that are or should be strapped to the coil have a good contact with their spade connections.

As for a 12v power supply at the pump relay when the ignition switch is on, that's ok and as it should be, or do you mean the pump is running all the time? as its the ECU that switches on the pump relay by completing the earth return from the relay.

Don't bother looking for relays under the drivers seat, u will find them behind the drivers foot well kick panel also the engine bay inertia switch only cuts the earth return from the pump, so no earth no pumping.

Tried changing relays over, I've got no power to maintain relays, the ecu does not put a live to operate it, if I put an earth to the injectors and a wire from the coil they spray fuel, I've checked coil wire to ecu, all is ok, I've even tried putting a new wire off the coil resistor to ecu, ecu gets ignition live and all earths are there, I wounded if there was a sensor that had shut the ecu down ,ie crank sensor, I've checked safety cut out switch under bonnet , all seems ok

You don't have a crank sensor, but I think it's time u had the ECU tested or even temporary replacement fitted to check.

I've tried an ecu off a running car and it does the same

poloracer877 said:

I've tried an ecu off a running car and it does the same

Click to expand...

Okay Still guessing but try an independent supply from +poss of the battery to the black terminal/wire of the coil and see if u can start the engine.

Note the reference to a working 6.8k resistor in this link http://www.britishv8.org/articles/rover-14cux-efi.htm

I read your post and I have exactly the same problem on my Range rover 3.9 EFI 1990. I am looking for a solution for severals months and I didn't find...
I know this post is from 2015, how do you solve this problem ?
Thank you for your help !

@discool
Do you know the solution of this problem ?
Thank you for your help.