Return style wiring HOW TO allowing OE type fuel pump actuation

[danny04mystic]

Setting the base pressure is a piece of cake. Post up in our vendor section if you want to start a new thread and I'll reply with pics and a writeup there.

Jared

i started a thread on it today actually: but i cant understand why the car runs so much richer when only changes were the method of delivery and deleting fpdm. the regulator sould still control the pressure and injector slopes etc...in the tune should be the same still. but i would like to know the best setting for this regulator. i know exactly how to set it just not 100% where it should be? check my other thread though please to see what ive gone through today! thanks for the help man, i was gonna pm you!

http://www.svtperformance.com/forum...ng-base-pressure-return-fuel-system-help.html

and ps. for those who are worried about the pumps running with key on for say listening to the radio or sitting in the car, you can turn the key backward for that and they dont run. only when in the on position but not accessory, so im ok with that!

 

[gouldbri]

I tried to wire my return style fuel system the way Malcolm suggests and I could not get it to work at all. I used to power the relays from the green/yellow wire and the everything worked fine but it was annoying to have the pumps run all the time.

I have the Lethal 1200RWHP return style fuel system with their wiring harness. I reconnected the green/yellow wire as it was stock and used the brown/pink wire to trigger the relays (blue wire on lethal harness) from the connector side of the fpdm. I then used the red/black wire from the connector side of the fpdm to ground the relays (black wires on lethal harness). with key on I get power out of the brown/pink from the connector of the fpdm but it seems the red/black from the fpdm connector side is not grounding the relays.

I was able to get the pumps to run all the time by just grounding the relays to the chassis and using the brown/pink to trigger the relays but as Malcolm said the pumps run all the time.

Is there something I have wrong here? any help would be appreciated.

Thanks

 

[gouldbri]

Nevermind my post above. Its working. When I turn the key on, the pumps turn on for a very short time. I thought it would have been longer but guess not. My next question is that if the car sits for a while am I going to have to cycle on and off the pumps via the key a couple times to get pressure in the lines? The pumps run for like a second when keyed on, I don't think this is going to be long enough to build pressure. I added a switch to ground the relays to the chassis just in case this is a problem. Thanks for the help guys!!!

 

[danny04mystic]

Nevermind my post above. Its working. When I turn the key on, the pumps turn on for a very short time. I thought it would have been longer but guess not. My next question is that if the car sits for a while am I going to have to cycle on and off the pumps via the key a couple times to get pressure in the lines? The pumps run for like a second when keyed on, I don't think this is going to be long enough to build pressure. I added a switch to ground the relays to the chassis just in case this is a problem. Thanks for the help guys!!!

yeah mine acted like that as well when i tried to wire through fpdm. a second or two of priming was enough to get the pressure up and the car ran good but when we went to tune it it acted really funny. i ended up wiring the system per the instructions.
and for those who are worried about the pumps running full time, as was i, they only run when the key is in the "on" position but not in "accessory" which is when turning key backward. so if you wanna sit and listen to the radio or something like that they dont run all the time and im cool with it this way. and i know its right and easier to tune this way prob as well. hope that helps.

 

[gouldbri]

So I checked my fuel pressure with the modified wiring that uses the fpdm to trigger the relays and the base fuel pressure was about 4psi lower than it was with triggering it with the 12V "key on" way. Also I got a P1237 - "Fuel Pump Secondary Circuit Malfunction". Basically an open circuit for the fpdm. I added a switch to ground the relays so that I can run the pumps all the time so that I can prime the system after the car sits for a while. I went to the track and ran the fuel system to the switched ground and lost 5 mph in the back half. Not saying that the wiring modification was the reason I lost the 5 mph but it is the only thing I changed since I last went to the track. SO a couple take aways that I learned. 1) using the fpdm to trigger the relays threw a P1237 code for me 2) for some reason I lost 5 mph in the back half 3) if you dont add a switch to ground for the relays you will be trying to prime the fuel system for a while with only running the pumps for a second or so. I am not saying this wont work but I think someone needs to talk to a tuner before making this modification. My two cents. thanks

 

[danny04mystic]

yeah agreed. i ended up wiring as per the instructions from lethal as my tuner had issues setting it up this way and we aggreed it was much easier to have it run off koeo/koer and to tune this way. works great and i dont see the need to have it wired any other way to be honest as if you want radio or something while the engine is not running just turn the key backward to accessory. pumps don't run then, only when key is in the run position do they run, and i have yet to have an issue starting the car this way either. they prime the line almost instantly and the gauge shows 40psi with in about a second of turning the key to on. i start it as normal as i would any other vehicle and have zero problems with the system whtsoever.

 

[gouldbri]

I put the wiring for the fuel pumps back to "key on" set up and the mph is back. Wiring through the fpdm was definitely the cause for the lost mph in the back half. I am sure wiring the pumps through the fpdm could work but something definitely needs to be changed in the tune.

 

[0-MYSTACHROME-4]

Im thinking of wiring my return system per Malcoms instructions but what need to be adjusted in the tune to make this all to work right and not have tuning issues? Gouldbri and Danny04mystic seem to be having issues, has anyone else had any issues to report or have a solution to make this all work correctly? Thanks!

 

[danny04mystic]

Im thinking of wiring my return system per Malcoms instructions but what need to be adjusted in the tune to make this all to work right and not have tuning issues? Gouldbri and Danny04mystic seem to be having issues, has anyone else had any issues to report or have a solution to make this all work correctly? Thanks!

i have been thinking bout this as well even though im happy the way mine is. but from my understanding you would need to change the fpdm table(s) to force max voltage at all times, as if you still had your factory pumps making them run at %100 full time, which would make the new pumps run constantly as they should and allow the pressure to adjusted via the regulator and not fpdm. not sure how exactly this would be accomplished as i am no tuner but i am somewhat knowledgeable on some tuning software just not sct. im sure this can be done easily for any decent tuner though. i have no plans to change anything in my setup however as i think its pretty good wired to key on, tuning is easier which means less time and more cash toward another mod, and if i need radio whilst i await my next beatdown i turn it bacward a click to accessory where the pumps don't run. why it would need to be ran through the fpdm i have no clue as it kinda perfect the way it was intended imho

 

[Tractionless1]

Has anyone figure out how to make this work with the Lethal Budget System. Seems like there were problems above and when the member reverted back to full on all was well.

 

[Bdubbs]

I planned on going this route with my fore level 1 return system. I'm a little confused, do I run the fpdm wires to the FC2 controller? Pictures would really help! Maybe I'll take some pictures during install so it will help out future members doing the install.

 

[cj428mach]

Anyone else besides Malcolm making this work? I really want my pumps to prime and act like stock when going return. Thanks

 

[cj428mach]

I can't get this to work. I'm running a fore setup with an FC3. I wasn't 100% sure on how to wire this so I used a relay. I then used the green/yellow wire to power the FC3 but had it being switched on and off with my relay. I then used the brown pink and red black wires to trigger my relay and complete the circuit. I didn't get anything.

As far as the tune I have it setup via Don Lasotas book.

Does the fpdm need to remain plugged in for this to work? I just removed the 3 wires I'm using from the FPDM plug and hooked them to my relay.

 

[jblood37]

I can't get this to work. I'm running a fore setup with an FC3. I wasn't 100% sure on how to wire this so I used a relay. I then used the green/yellow wire to power the FC3 but had it being switched on and off with my relay. I then used the brown pink and red black wires to trigger my relay and complete the circuit. I didn't get anything.

As far as the tune I have it setup via Don Lasotas book.

Does the fpdm need to remain plugged in for this to work? I just removed the 3 wires I'm using from the FPDM plug and hooked them to my relay.

I think it would be cool to have pumps prime like factory, but if I couldn't get it to work I'd just wire everything like FORE suggests. I don't know if having the system prime and stop is worth the aggravation of figuring out how to wire it to make it work perfectly.

 

[cj428mach]

I tried changing a few things in the tune after reading this

http://mustangforums.com/forum/4-6l...42433-return-style-fuel-pump-switch-wire.html


and thought that would have taken care of it but it didn't. It's pretty frustrating, I hope someone can post some more about how to do it. I put 2 different tunes on my car last night and took it out and tried one. Then when I went to load the other one the pumps were running full time. What a pain in the ass.

 

[MalcolmV8]

Sounds like you guys are not wiring it correctly. Please post a wiring diagram of how you're wiring it and I'd be happy to help.

 

[cj428mach]

Sounds like you guys are not wiring it correctly. Please post a wiring diagram of how you're wiring it and I'd be happy to help.

Thanks Malcolm. I'm running the FC3 and I'll use the picture below help explain it.

I have
Terminal 30=green/yellow wire
Terminal 87=remote trigger on FC3
Terminal 86=brown/pink positive from FPDM
Terminal 85=red/black ground from FPDM

http://www.12voltplanet.co.uk/user/Driving_light_relay_wiring_diagram.png

If it makes a difference, I didn't splice any wires. I just removed the green/yellow, brown/pin, red/black terminals from the FPDM plug and plugged them into my relay harness with some male terminals I had from an old harness. I've tried it with the fpdm plug, plugged into the fpdm, unplugged from the module, with terminal 86 & 85 swapped, I made the changes in my tune that was recommended in that link I posted. I really don't know what else there is to do.

I currently have hooked up the green/yellow to 86 and my FC3 trigger to 85 and this lets it run with the key on all the time and that's how I've left it until I figure it out. Thanks for any tips you have.

 

[MalcolmV8]

The key here is to use this from the FPDM

Pin 10 = BN/PK (normally fuel pump positive)
Pin 3 = RD/BK (normally fuel pump negative)

Take those two wires and use them to activate your relay. Get that working first and expand from there. If that doesn't work nothing else will.

I get lost following all the other explanations everyone has of wire X goes to wire Y etc. That's why I say make a wiring diagram of exactly what you're doing if need be.

 

[cj428mach]

Does the fuel pump duty cycle need to be at .5 or at .999 in the tune? I read somewhere that it needs to be .5 and the ecm will multiply that value by 2. I also read that you need to set it at plus 70%. I have followed the tune setup for return like Don suggested in his book.

The key here is to use this from the FPDM

Pin 10 = BN/PK (normally fuel pump positive)
Pin 3 = RD/BK (normally fuel pump negative)

Take those two wires and use them to activate your relay. Get that working first and expand from there. If that doesn't work nothing else will.

I get lost following all the other explanations everyone has of wire X goes to wire Y etc. That's why I say make a wiring diagram of exactly what you're doing if need be.

 

[MalcolmV8]

Does the fuel pump duty cycle need to be at .5 or at .999 in the tune? I read somewhere that it needs to be .5 and the ecm will multiply that value by 2. I also read that you need to set it at plus 70%. I have followed the tune setup for return like Don suggested in his book.

My Fuel pump voltage table has all cells at max 15.
Returnless Fuel Pump --> Fuel Pump Voltage Table

However I will point out even with the stock returnless settings the FPDM will still activate the relay. It's just not suited for continuous use while driving because if the duty cycle goes to low the relay could turn off.