Hi members ,

Please can someone assist me with an electrical problem involving njectors , i have a mp9 ecu which is connected as per the wiring diagram , i have checked all wires as per the mp9 wiring diagram the car will turn , ignition comes on , there is spark , there ls fuel but my injectors are not pulsing. I have tested them and there is no power goin to them , although there is power goin to the ecu pin 21 if im not mistaken.

I also wanted to ask if there should be power going to the ecu allways or should there only be power when ignition is on.

I have also checked all fuses and relays and all seem to be working.


I am new at this and hope i have explained properly , please let me know what i can check or what should be check to try amd narrow down problem.

Thanks for any help in advance.

Welcome to the Forum...

Did you wire in a fuel pump relay? The injectors share the common Pos with the fuel pump Pos, switched by the relay. The actual firing pulse from the ECU is a -VE (ground) condition.

The complete MP9 ECU pin-out:

Thanx for the reply.

The relay is in the correct place as i didnt remove any relays and did not wire up any relays. All i did was reconect the ecu according to the diagram. So maybe i blewup the relay if thats posible and also all fuses are still ok.

If i turn on ignition i get a humming noise in the engine bay , which goes off after a few seconds. I am not sure if this is the fuel pump or tps .

Which relay is the fuel pump relay , i can maybe post some pics of my fuse and relay box to make it easier to check.

neel wrote:Thanx for the reply.

The relay is in the correct place as i didnt remove any relays and did not wire up any relays. All i did was reconect the ecu according to the diagram. So maybe i blewup the relay if thats posible and also all fuses are still ok.

If i turn on ignition i get a humming noise in the engine bay , which goes off after a few seconds. I am not sure if this is the fuel pump or tps .

Which relay is the fuel pump relay , i can maybe post some pics of my fuse and relay box to make it easier to check.

The humming sound is your idle motor doing a self-test of sorts. There was a thread here a couple of weeks back showing pics of the fuel pump relay, I'll see if I can dig it up...

Here you go: http://www.vwclub.co.za/phpbb3/viewtopi ... 3&t=146798

Are the relays for a 1.4i 2003 model citi golf also on the same side , bcoz i also have relays on the lefthanside where my fuse box is.

neel wrote:Are the relays for a 1.4i 2003 model citi golf also on the same side , bcoz i also have relays on the lefthanside where my fuse box is.

I'm not too sure on the square dash Citi's, I had a 2005 Velo so that's what I'm clued up on. Do some basic fault finding, if your fuel pump runs then the injectors should work as well....

I have foumd a relay that is rusted inside , it has 6 pins. I am not sure if that is the fuel relay.

Thanx for the help torker.

I sorted the problem

1. Had 2 change fuel pump relay
2. Stupid fuel pressure regulator packed up , i only figured this out wen i crimped pipe returning to fuel tank.

Such a easy fix .

Glad you came right...

Good day

I seem to have the very same problem with my golf 1.
I have recently replaced my fuel pump, now the car wont start.

Fuel is being transferred to the Filter but the injectors are feeding fuel to the plugs.
Plugs are sparking.

I have checked the main relays with is located near the battery they are fine.

what else can I do ?? could it be the wiring?.

please help

El Breezy wrote:Good day

I seem to have the very same problem with my golf 1.
I have recently replaced my fuel pump, now the car wont start.

Fuel is being transferred to the Filter but the injectors are feeding fuel to the plugs.
Plugs are sparking.

I have checked the main relays with is located near the battery they are fine.

what else can I do ?? could it be the wiring?.

please help

Could be that the new pump is not pushing high enough pressure, should be 3 bar at least. Why did you replace the old pump?

guys i need help...the wire that powers the injectors where does it connect to on ecu or where? i want to change from spitronics to standard mp9 ecu

the +ve for the injectors is a common wire going to all 4 injectors, this normally gets connected to the +ve feed for your fuel pump.

sorry but im very confused what +ve is? that is a ground right? so it doesnt go to the fuel relay perhaps?

Sorry +ve is positive, meaning 12v and not ground

so i can run it with the fuel relay? u dont have a whatsapp number or something? then i can send u pics of the lom etc need some help or email address

Yes normally the fuel pump relay is used to feed the injectors and the fuel pump.
Ugen@kznclearing.co.za

My Citi setup has the injector relay triggered by the ignition and a seperate fuel relay triggered by the ecu. You could have the low current circuit running through both relays, just don't let the fuel pump relay be triggered by the ignition.

so basicly i can run my injecters with ignition? thats pin one on all the injectors? and then the fuel pump relay with 86coming from pin 25 from mp9 ecu...85-12v from starter...30-12v battryy and 87 from positive pump...i got that lay out on one of the pages?

safiallie wrote:so basicly i can run my injecters with ignition? thats pin one on all the injectors? and then the fuel pump relay with 86coming from pin 25 from mp9 ecu...85-12v from starter...30-12v battryy and 87 from positive pump...i got that lay out on one of the pages?

Pin 1 on all the injectors must be commonned to a Pos 12V supply voltage - this can be connected to the ignition switch of the car or the Pos 12V supply going to the fuel pump. The latter is controlled by switching the fuel pump relay from the ECU when priming or when detecting rpm signal. Pin 2 on the injectors are wired directly to the ECU injector outputs, the trigger comes in the form of a Neg (0V or Earth) pulse from the ECU. Pos on Pin 1 and Neg on Pin 2 of the injector will activate the injector and turn it on for the period of time determined by the programming in the ECU.

thnks alot bro...and the relay set up that i did put up does it sound right? it gets 2 12v pos? pin 254 is grund and the the posiive of the pump?

guys pin 23 does it connect straight from ecu to coil pin 3 or must ther be another wire from ig switch conect with it? help thansk

safiallie wrote:guys pin 23 does it connect straight from ecu to coil pin 3 or must ther be another wire from ig switch conect with it? help thansk

You can bring the wire from the ignition switch to pin 23 on the ECU and then run another wire from pin 23 to pin 3 on the coil, or you can have separate wires from the ignition to the ECU and the coil.

Complete MP9 wiring diagram:

torker can i have your email address plz? want to send you a pic