W124 dual fuel pumps - MBClub UK

Brabus3.6 · 08-08-2006, 02:22 PM

Exactly how does the dual fuel pump setup work? I'm installing a wireless immobiliser which is designed to take the fuel pump out but as I have 2 it'll take a little thought! Will taking 1 out prevent the car being started? If not then are they active simultaneously always or is there ever a time when just one if left on (perhaps at idle)? If they're both always on I can get around it with some relays

. Cheers guys.

Dieselman · 08-08-2006, 07:21 PM

I would've thought they just operated simultaniously. How are they positioned in the fuel lines, in parallel or seies or another configuration.

I suspect in parallel and there are two so that full requirement can be met without any pressure drop.

grober · 08-08-2006, 10:27 PM

from this picture they appear to be in series. I would guess they are powered from the same source.You should find the power supply lead/leads under the rear seat.

Brabus3.6 · 09-08-2006, 03:06 AM

Thanks for the input guys. I suppose fuel pump relay would be the easiest place to hijack this connection. Fully immobilised now though

grober · 09-08-2006, 09:34 AM

Disabling the fuel pump relay as well is a good idea because it prevents fuel from being pumped into an engine that doesnt fire! Thats assuming you didn't do anything to the starter motor circuit

and disabled the ECU instead! Dont answer that.

08-08-2006, 02:22 PM	#1
Brabus3.6 Hardcore MB Enthusiast Join Date: Apr 2004 Location: London/Oxford Car: 1989 Brabus 3.6 Saloon Posts: 109	W124 dual fuel pumps Exactly how does the dual fuel pump setup work? I'm installing a wireless immobiliser which is designed to take the fuel pump out but as I have 2 it'll take a little thought! Will taking 1 out prevent the car being started? If not then are they active simultaneously always or is there ever a time when just one if left on (perhaps at idle)? If they're both always on I can get around it with some relays . Cheers guys.

08-08-2006, 07:21 PM	#2
Dieselman Hardcore MB Enthusiast Join Date: Jul 2003 Car: Peugeot 403 Convertible Posts: 28,838	I would've thought they just operated simultaniously. How are they positioned in the fuel lines, in parallel or seies or another configuration. I suspect in parallel and there are two so that full requirement can be met without any pressure drop.

09-08-2006, 03:06 AM	#4
Brabus3.6 Hardcore MB Enthusiast Threadstarter Join Date: Apr 2004 Location: London/Oxford Car: 1989 Brabus 3.6 Saloon Posts: 109	Thanks for the input guys. I suppose fuel pump relay would be the easiest place to hijack this connection. Fully immobilised now though

09-08-2006, 09:34 AM	#5
grober Hardcore MB Enthusiast Join Date: Jun 2003 Location: Perth, Scotland Car: W204 C200CDI Estate Posts: 14,457	Disabling the fuel pump relay as well is a good idea because it prevents fuel from being pumped into an engine that doesnt fire! Thats assuming you didn't do anything to the starter motor circuit and disabled the ECU instead! Dont answer that.

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