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MG MGF Technical - Wiring help - fuel pump

Further to my earlier thread on the fuse for the fuel pump - I have now found that this is not the cause of my intermittent fuel pump fault.
The AA came out to help me today and found that I have no power going to the relay for the pump. He suggested I get an auto electrician to replace the wire for the fuelpump from the ECU to the relay. I think I can manage this myself - but need to know which wire feeds the power for the fuel pump from the ECU to the relay (I believe it is grey/purple from the relay to the punmp).
Hope someone with a wiring diagram can help.
Jason
Jason Harris


Hi Jason,

to answer Your question ; the cable is "BP" = black / purple going from ECU as "Fuel pump relay drive". NOTE !! What the ECU actually does is to take that wire to GROUND ! The +12 Volts is already present at the relay if all fuses etc. are OK. To get the pump (and car) running it is safe to take BP -cable to ground for a test. More tech ; In the ECU is a switch transistor , "open collector" that normally does the switching to ground. If that transistor has seen full +12 Volts without any load in between when going to ground it is most probably destroyed !
A short-circuit in the fuel pump relay coil will give this kind of problem .

Regards , Carl.
Carl

Carl,
thanks for the answer - I don't think my ECu is trashed as my problem is intermittent - most of the time it is okay!
I think I will try replacing the relays and see if the problem persists - anyone got a second hand realy pack I could try?
Jason
Jason Harris

> anyone got a second hand realy pack I could try?
:)
Me, but UK based chaps should reply at first IMO
:)

Jason,
according to Carls instructions the schedules could be also required
http://www.lame-delegation.de/mgf-net.de/schedules/index.htm

HTH
Dieter
Dieter Koennecke

Dieter,
I have sent you an E-mail, Thanks for the link - really useful.
Jason
Jason Harris

got it and just replied.

For identification:
http://www.lame-delegation.de/mgf-net.de/sales/dcp_3829.jpg
attached to the rear of the ECU.

Dieter
Dieter Koennecke

your problem is more than likely the ecu it starts out as an an intermittant fault but eventully the ecu packs up all to gether the black purple wire turns from an earth to a live when its running ok the wire will be an earth when the fault occurs it will switch to live
mark the tech

Hmmm, may be he is right. He never failed, did he ?

Shall I send it complete ?
ECU with main relay from MPI VIN SARRDWBGMWD029593 ?

Dieter Koennecke

No answer by email from Jason, so I write the details here:
The ECU I can send is MKC104111.
bar code label is marked with No. *2907104111*

;-) I can't withstand, but open the ECU now and make some pictures :)))
Know about electronic distortion terms, no fear.

The relay is YWB100710
42V RTV is also written to that label.
Dieter Koennecke

This thread was discussed between 19/01/2001 and 21/01/2001

MG MGF Technical index

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