Fuel pump hardwire

[gerryeddie]

For those of you who have hardwired your fuel pump in GSR/Evo1-3, where have you positioned the relay? In this case, the battery is in the boot.
I have all the parts needed, just thinking about where the relay will go and where to run the wiring.

 

[4piknup]

Your battery is in the boot, your pump is near the boot. No brainer to put it near there somewhere.

Other guys say to use the fat pump wire to switch the relay, but I think its better to use the ecu wire as it will bypass the mfi relay. You would need around 300 ohms resistance on the primary of the relay so you dont upset the ecu. This shouldnt be any issue as the aircon/radiator etc are switched by the same part of the ecu.

I would run the (white/red?) Ecu wire to the rear. Or at the mfi relay unpin the mfi plug and connect the white/red to the (black/blue?) That runs to the pump at the rear. This will give you a ecu run earth switched wire down to the pump. Use that wire to switch the relay and run a fat wire to the pump.

Does that make sense? Check your wiring colours etc as im only working from memory

 

[evo-gsr]

What he said basically..^ relay should be somewhere near the back seat area.

 

[CLuTZ]

Put it inside the battery box

 

[khubner1]

Your battery is in the boot, your pump is near the boot. No brainer to put it near there somewhere.

Other guys say to use the fat pump wire to switch the relay, but I think its better to use the ecu wire as it will bypass the mfi relay. You would need around 300 ohms resistance on the primary of the relay so you dont upset the ecu. This shouldnt be any issue as the aircon/radiator etc are switched by the same part of the ecu.

I would run the (white/red?) Ecu wire to the rear. Or at the mfi relay unpin the mfi plug and connect the white/red to the (black/blue?) That runs to the pump at the rear. This will give you a ecu run earth switched wire down to the pump. Use that wire to switch the relay and run a fat wire to the pump.

Does that make sense? Check your wiring colours etc as im only working from memory

seem like extra work why remove or bypass wiring thats already there in order to add your own?

 

[Dave_GSR1.8]

So I have exactly the same question (my nice new walbro currently running on stock wiring) but my battery is in the stock location, I had assumed I would put my relay as near as possible to the MFI relay under the dash and switch it with the main pump feed (circled in the attached PDF) but your comment Jack worried me, are there any problems in using the pump power feed to switch the relay ?

Apologies for hijacking the thread but I figured that as it was more questions about the same issue that it would be OK

Not 100% sure about the wiring diagram, it is from "CC Lancer Coupe & Mirage General Electrical 92-96.pdf", the nearset electrical manual I could find for the CC GSR, it looks pretty close for the things I could identify

 

[4piknup]

Only that you are using a relay to trigger a relay. You have doubled you potential problems for no gain.
You have changed from oem neg relay trigger to pos relay trigger.
And dougmo would freak out at the extra weight.

Look its not that big a deal,
Dont read too much into it. Its my opinion and there is thousands wired the other way straight off the pump wiring.

 

[EVO-00X]

Put the relay as close to the fuel pump cradle as possible.
Use the oem black and blue fuel pump power wire as the trigger for the relay because that's the only thing its good for. OEM voltage at the black/blue wire is said to only provide between 7-10 volts fluctuating under load to the stock fuel pump, so it will definitely not provide the voltage you need to make a Walbro flow to potential because those little suckers need a good stable voltage supply under boost.
The reason I say to mount the relay as close to the fuel pump as possible is because you can run a good thick gauge wire from the battery to the relay with very negligible voltage drop, but there aint no way you will get a good gauge wire from the relay into the fuel pump cradle. So the train of thought there is to keep the smaller gauge cable as short a distance as possible between the relay and the fuel pump due to voltage drop in smaller cables.
I have done that same thing with my car and the relay sits under the driver's side back seat next to the white plastic loom connector that joins the front loom to the rear interior loom. I cut a little slot in it and put it inside the plastic shroud.
Im getting 14.2 volts to my battery and I reckon around 14v at the single intank Walbro. I'm boosting 30psi on pump fuel and its doing its job.
See pics attached of mine. Pardon the old crappy image, it was some time ago lol

 

[khubner1]

mine and my brothers cars both see 13.6 at the cradle so i'm good

 

[gerryeddie]

Thanks fellas

 

[MDK87]

If one wanted to replace the wires all the way to the pump, does anyone know of a neat and safe way to pass it through the cradle?

 

[EVO-00X]

Yeah connect as big a wire as you can into the connector plug that goes into the receiving plug on top of the cradle. Then use a thickness of wire that you can work with internally inside the pump. The fuel pump should come with its own wires you can use. You will have a short bit of thinner wire overall but that's OK over a very short distance as you're talking less than 20cm.

 

[Dave_GSR1.8]

Well, spent a pleasant day putting in a fuel pump relay as per EVO-00X's post, so far looks promising in that it now revs out (was cutting out before), willl know for sure in a few days.

Thanks for the info EVO-00X!

 

[Ian91]

Put the relay as close to the fuel pump cradle as possible.
Use the oem black and blue fuel pump power wire as the trigger for the relay because that's the only thing its good for. OEM voltage at the black/blue wire is said to only provide between 7-10 volts fluctuating under load to the stock fuel pump, so it will definitely not provide the voltage you need to make a Walbro flow to potential because those little suckers need a good stable voltage supply under boost.
The reason I say to mount the relay as close to the fuel pump as possible is because you can run a good thick gauge wire from the battery to the relay with very negligible voltage drop, but there aint no way you will get a good gauge wire from the relay into the fuel pump cradle. So the train of thought there is to keep the smaller gauge cable as short a distance as possible between the relay and the fuel pump due to voltage drop in smaller cables.
I have done that same thing with my car and the relay sits under the driver's side back seat next to the white plastic loom connector that joins the front loom to the rear interior loom. I cut a little slot in it and put it inside the plastic shroud.
Im getting 14.2 volts to my battery and I reckon around 14v at the single intank Walbro. I'm boosting 30psi on pump fuel and its doing its job.
See pics attached of mine. Pardon the old crappy image, it was some time ago lol

Where did you earth the relay rob?

 

[Dave_GSR1.8]

If it helps I just earthed it to a self tapper that had been installed to hold the carpet down, just near where the relay was installed, I didn't bother re-using it to hold the carpet down again.

I can get a picture if you want.

 

[Ian91]

No that's ok, was just curious because I had mine under one of the seat belt buckles and the pump wouldn't go, moved it to under the actual seat belt mount and it was fine

 

[4piknup]

Im not sure how long a self tapper will be good for. If it has trouble thats the first place I would look.

 

[evo-gsr]

Sounds dodgy to me.

 

[Ian91]

Im not sure how long a self tapper will be good for. If it has trouble thats the first place I would look.

I reckon since I had issues with it wrapped around a 10mm bolt Lol

 

[Dave_GSR1.8]

Yes, I have to admit I was not sure where else to put it, if anyone can suggest a better location I would be grateful! In the absence of any obvious earthing point I just picked up that existing self tapper, it looked nice and shiny where the thread had been cut, and it torqued up really well. Where have other people earthed their relays? FWIIW my battery is in the stock location.

Ian91, by seat belt mount do you mean on the door piller, below the inertia reel ? That could be a good idea... nice and close...