P8 pro wiring fuel pump

Wiring best practices and loom building technique
Benmk1
Posts: 15
Joined: Wed Jul 17, 2013 3:35 pm
ECU Model: P8 Pro

Re: P8 pro wiring fuel pump

Post by Benmk1 »

Just one more question sorry would u recommend switching the earth instead of switching the live? The just fuse the ignition live the relay? Thanks ben
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: P8 pro wiring fuel pump

Post by Rob Stevens »

Yes just put the relay in the +12v fused line, that way you can use the same fused 12v supply to go on the coil of the relay.
You also mention 2 fuel pumps one HP and LP one I assume the LP one feeds a fuel swirl pot or something, in that case yes just wire them together, or better still use 2 relays and 2 fuses, better for trouble shooting. I also include a switch to emulate the ecu.
Benmk1
Posts: 15
Joined: Wed Jul 17, 2013 3:35 pm
ECU Model: P8 Pro

Re: P8 pro wiring fuel pump

Post by Benmk1 »

Yer I'm going to use two relays and two fuses think that's the best way thanks alot for your help so would pins 30+87 be both earth now if I was switching the earth?
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: P8 pro wiring fuel pump

Post by Rob Stevens »

Hm, don't quite understand the question, just do the following :-
Wire the -ve of the fuel pump to a permanent good earth
Wire the +ve of the fuel pump to 87 on the relay
Wire a fused +12v to 30 on the relay - link this same terminal to 86 on the relay
Wire 85 to the fuel pump output on the ecu pin 41 on the P8
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