Teach me about the evo fuel pump wiring then help me build it in my car.

[the_mork]

My evo9 fuel pump is overrunning my stock FPR horribly. I would like a way to turn it down at low load like the evos do but I'm just not good enough with electricity to fully visualize what that takes.

I have an evo8 ecu in my car so the only challenge is figuring out how to wire it up properly. My understanding is that the evo system uses dual electrical feeds, one of normal medium gauge wire and another that has a resistor built in to lower fuel pump voltage and then it uses a switch to move between those circuits.

Can anyone with a little bit of electrical background give me a list of the sort of things that I might need? Does anyone know the output voltage of the fuel pump switching relay or if it is in fact a switched ground?

I can solder and I have a general idea of what is going on so if I can gather the parts and someone can point me in the right direction then I can write up an article on how to do this for evo8 ecu swapped cars. I don't know about anyone else's opinions but it seems to me like $30 in electrical parts and wire beats the hell out of $150+ for a FPR especially when most people rewire their pumps anyway.

 

[turboglenn]

NOt to knock the idea, but unless you're done with modding your car, it seems like this would be too extensive of a bandaid for most people considering that the OEM FPR needs upgraded anyway at some point due to fuel flow requirements.

I ran a wally 255 for a long time with OEM 2g wires to it and it never overran the stock FPR, once i wired it up with 10gauge then i had some trouble keeping the flow under control. If you've already re-wired that EVO pump then you might wantto go back to the 2g OEM wires as they are so small and drop enough voltage to kill the performance of any good pump. Then you could just have a relay triggered by boost to engage the larger feed wire thus kicking up the voltage and performance of the pump when you need it.

I've tuned quite a few subaru's using UTEC and some other system similar to it and have ran into issues tuning because of the variable voltage system they use from the factory. By-passing this system with a good wire solved those issues. Based on this i'd personaly try and stay away from variable voltage, but it may be worth while if you're at the end of your tuning goals and are searching for OEM drivability, then it may come in very handy. or would be killer for keeping a sleeper setup

WHat i'd REALLY like to see is some one come up with a cheap DIY "boost-a-pump" that could be built reliably and be simple enough for your average guy that can solder to build, and staying away from too much circuitry construction. Most of us can build simple little things with a few caps, resistors, diodes and voltage regulators..but getting into advanced bread boards (like building a megasquirt from scratch) is a little too much both in complexity and time consumption for some of us to want to bother with building...(the places that sell pre-built megasquirts have themselves a good little thing going because although i CAN technically build one, i'd rather just spend the 400 ucks to have one that some one who is very knowledgable in these units built and tested instead of me burning up hours of time on a customer car trying to nake and configure one from scratch. And not having the indepth knowledge to troubleshoot the components or different areas of the units circuit i would burn up a LOT of hours

 

[the_mork]

I am close to where I want to go with this car for now. I am also incredibly strapped for cash at the moment. I am definitely overrunning and I'm using stock wires. If I could build a little system that was reliable and easy to put in as well as fairly cheap then I could save a lot of people money on a FPR.

I've always felt that low key and sleeper were positive things for the majority of modified cars. There is nothing shiny under my hood except for my strut bar and my bov. I like it like that.

 

[turboglenn]

Oh I wasn't knocking slepers by any means... IF you look at my car the appearance as still as far towards stock as i could keep it with the only visual clues of performance being the thermal muffler and FMIC (didn't want to paint it and kill the cooling)

Also wasn't knocking the idea, especially for those 2 reasons of sleeper function and drivability improvements if you won't eventually need an AFPR for other reasons, so i think you're well justified in the build of this if you can get it going. I'm definitley interested, so don't loose motivation just because no one has probably done it or if people say you shouldn't.

BTW...what's happening that gives away the over running? Is there a possibility that there is something else causing the issue? I've never used an EVO pump and can't think of their flow off the top of my head. BUt i would imagine it flows at or less than a 255 and i've seen a lot of 255's used on stock fuel systems without issue.... SO i'm a little baffled as to what signs of overrun you're getting.

 

[the_mork]

I'm seeing a significant difference in my low ltfts to my mid ltfts. This was on a factory tune, then a modified tune, then an SD tune. I even tried turning closed loop off and I was reaching a target of 18:1 at low load idle before the actual AFR was reaching 13:1 but as soon as IPWs went up everything acted normally.

IIRC an evo9 pump is slightly larger than a 190 but also IIRC is more efficient at low voltage though I couldn't find any hard number to back up the voltage efficiency.

 

[Ceddy]

You could wire it up with one relay feeding the pump with a resister inline, and the second relay just a straight feed to the pump.

The Evos use three relays, with two of them interlocked.

I think it may more trouble than its worth with a single pump setup.

I like the evo dual pump setups though, with a single pump turned on then two pumps on.

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[bling5tatus]

who wants to take a boost a pump apart so we can make something similar to it?

 

[tkelly27]

If you have a spare regulator you could try this

The Old One - Energy Dynamics : Articles

 

[the_mork]

I've seen that but the discussion of its implementation that I've seen suggests that it wont help on a DSM where the major restriction is actually the fuel outlet. Now maybe it would be possible to cut the outlet down and weld a larger fitting on.

Ceddy, I'm not actually good enough at reading electrical diagrams to get the into my head on how to wire it together. I haven't looked at that diagram closely but I think if I study it for a bit I can get it. I would be perfectly happy with modifying the stock FPR to get it to flow enough for my needs and maybe that is the direction that I should go.

Does anyone have any solid information on the limiting factors of the stock FPR? If it is just the return then I might hack one apart and see if I can make it work better.

 

[Wufei]

Here're some numbers for the Evo 8 pump, which flows a little less than the 190. Sounds like the 9 pump flows more than the 8's? RRE Instructions

 

[mike96]

i have been begging over on EVOM for someone that is better at dissembling the ecu than me to try and find the control for the fuel pump relay wiring so it could be used for something else like nos or meth control. any way i had to doodle a little cause i like to doodle here you go. all you have to do is cut your factory wiring and solder in a resistor (sorry i don't know what size or wattage resistor at this time). then add (either by cut and solder or vampire splice) a wire on either side of the resistor and wire it to a relay. now here is the only tricky part is the relay is held electrically open (backwards compared to 95% of the relays in a car) so you might have to search to find the right one. last time i searched you had to order the relay from somewhere on-line or order a factory EVO8 relay.

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[the_mork]

Nice, that makes much more sense to my diagram-retarded brain. When I get some time again in a couple weeks I'm going to look into it. I also noticed in the fabrication section there is a guy working on making the stock FPR not suck.

 

[mike96]

my bad i am sorry, i had to make a small change to that diagram. the relay gets wired from the ecu to a 12V source not to a ground..... on the EVO the relay gets the 12V power from the fuel pump positive wire but i would think you can get it from anywhere... sorry about that.

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[the_mork]

I finally have some time now that school has started and the first week is over. I think I'm going to start gathering materials and working on this in the near future. The only things that will cost me extra over a standard fuel pump rewire will be the relay and resistor so even if I can't get it to work I wont be out much. I'm really hoping that this will save me some money in the long run because I'll be able to go to a full time open loop tune and run 15.3:1 on the highway.