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The mkiv Supra Owners Club

Wire for fuel pump


add heywood
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I have an aftermarket fuel pump. When I turn the ignition on the pump starts up, therefore you cant sit in the car with the ignition on to listen to the radio while waiting etc. Now I know this is no the best thing to happen incase I ever have a crash and the pump doesnt turn off.

I'm wanting to tap into the power so I can add a simple switch to be able to turn the pump off with the ignition on.

Where would I be best to tap into the power? Is there a specific wire near the ignition barrell that goes to the fuel pump. Any info on colour, location etc would be much appritiated.

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The pump should not run while the ignition is on the '2' position. If it does then someone has bodged the wiring, it's very dangerous for the reason you state.

 

Have a look at the top of the pump and the pump ECU to see if any of the wires have been spliced. I would expect it's either had the '12v' mod done, or similar, these are usually done at the fuel pump ECU plug.

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The fuel pump ECU is mounted behind the inner wing on the passnger side. A pic is below, it's from an old pic but added an arrow to show the panel which the ECU sits behind. Ignore the wiring, it was hacked extensively.

 

As your car has a mapped ECU, it's advisable to check out whats been done first before making any changes. Can you post a pic of the top of the fuel tank and the fuel pump ECU? It should help diagnose whats been done.

Fuel pump ecu2.jpg

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Ok got some pics, apologies for quality had to use the phone to take them.

image

Looks as though there have been no modifications to the actual ecu, all wires look undesturbed wrapped together.

 

image

image

Blue wire (top centre of pic 1) was earthed to bodywork and joined to a red wire inder the black foam at centre if pic 1. The red wire was not attached to anything when I undid the black circular top of petrol tank (as seen in final pic below).

image

image

The 2 wires at the centre of pic 2 have plastic connections at their ends but are not connected to anything

image

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Great pics, that helps a lot.

 

I can't remember what those two spliced wires on the top of the tank do right now, but can have a look tonight if no one else posts up.. I think thats a 12v mod though with the pump controlled by the ECU. Can you check where the red sheilded wires at the top of pic 3 go to? I imagine it will be your ECU.

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Sorry it's taken so long to reply to your question Homer.

 

Ok so I've looked at the wires you asked and they disappear down the side of the car towards the rear speakers. My guess is these are the power source wires and are linked to the ignition circuit at the front of the car somewhere. For now I've tapped into the earth wire from the top of the fuel tank so at least I can turn it off with the ignition on.

 

Obviously this isn't ideal so if you know how to reverse it, that would be great. Cheers

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Thats a nice easy workaround for the time being.

 

Those two wires most likely drop down behind the speaker panel, then run along the passenger sill to the ECU area. The plastic sill part can just be pulled off at the back with one push-clip at the front, take it out and you should be able to see where the wires go to

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yep true, but this is japanese wiring lol..

 

i have learned from past dont fiddle with jap wires as it might cause more headaches...

 

i had similar wired pump in my rex.. i just put a switch to it..

 

Lol, yeah I was thinking the same. If I start messing around too much there will be a "my car won't start" thread being posted soon.

 

Ill have a look see where these wires go to around the main ecu and report back. The switch works fine for the time being though :) Cheers

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