By the way the return is the stock feed line
Return style wiring HOW TO allowing OE type fuel pump actuation
- Thread starter MalcolmV8
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That layout looks good. What brand fuel pressure regulator? Is it perhaps not set correctly?
If you manually power up the pumps (engine off) what is your regulator set to pressure wise? Lets say 39 PSI. Then when you turn your pumps off does it just drop to zero?
If you manually power up the pumps (engine off) what is your regulator set to pressure wise? Lets say 39 PSI. Then when you turn your pumps off does it just drop to zero?
Its an aeromotive fuel pump regulator and i will try switching them on manually, but i think there is an internal tank leak bc i lose pressure and i can hear a dripping sound inside my tank
Confirmed dripping sound inside tank, had pinholes in gas linefrom pump to the y at the hat, will be running 8a gauge wire to the pumps since I'm down here
Stock corrugated line in a stock yet?
Has anyone tried this with Lethal's new harness? I'd like to have the pumps setup this way but haven't figured out how.
Good info in this thread, subn so I can report back when I'm ready 
I'm about to wire my LP BRSF I will run it like the diagram I just have one question does the EEC know that this is return now? If not wouldn't the FPDM lower the ground signal when the fuel pressure get to 40psi in turn the relay would loose its ground just like the returless fuel system.
I'm not sure about this 40 PSI change but to answer your question yes the ECC knows you now have a return style fuel system. You need to change that in your tune.
Does anyone know where in the tune I can make sure that my pumps run at 100% duty cycle all the time? I just finished going to a return style fuel system with triple in tank pumps and wired up my relays using this method and FPDM to prime the pumps but it seems like my pumps shut off after I'm done cranking it and it dies.
NM I found it.
There's more than just that one field. You need to set all cells in the fuel pump voltage tables to max. Usually 15 volts. In scalars you need to adjust fuel pump gain integral term, fuel pump gain derivative term, and fuel pump gain proportional term to all zero I believe. Also desired drop across injectors needs to be set 4 PSI below your base pressure. So you set your fuel pump regulator to 39 PSI (key on, engine off) then your desired drop across fuel injectors in the tune is 35 PSI.
I believe there was also a scalar in system switches called "fuel pump type" that needs to go to 0. I just looked at this recently so remember them pretty well but not on my tuning laptop right now so can't reference them all but I believe thats all of them.
I highly recommend an SCT manual of sorts to get you all the details such as these. There's a few options out there from Don Lasota, Greg Banish and so forth.
I believe there was also a scalar in system switches called "fuel pump type" that needs to go to 0. I just looked at this recently so remember them pretty well but not on my tuning laptop right now so can't reference them all but I believe thats all of them.
I highly recommend an SCT manual of sorts to get you all the details such as these. There's a few options out there from Don Lasota, Greg Banish and so forth.
Thanks! I have Lasota's manual. I just overlooked the one cell to change. Also, I'm trying to run E85 and changed stoich to 9.7:1 and bumped up fuel pressure to 55psi and desired drop across injector to 51psi. Sound good?
I still cant get it started on E85. I added timing and it got better but still wont start. Any Ideas? Thanks!
What's the wideband showing? You may have to wire it up directly to battery for this so the wideband and gauge do not power off during start so you can monitor it constantly. I assume you had a pump gas tune prior so MAF transfer curve is dialed in already? What injectors? I found 80 lb injectors are so way off you have to hack the MAF transfer curve for them. This means when switching from pump to E85 some hacking of the MAF is required. Even though in theory that should not happen.
I appreciate the help Malcolm! That's the problem, I can't read the wide band while cranking. So, wire it directly to the battery? I dialed in the pump gas tune with the 39lb injectors and swapped the 39's with 80's and return system at the same time. I did not tune for the 80's on gasoline and went straight to the E85. I thought about it but didn't want to worry about draining the tank and emptied it when i swapped the pumps. So, do you think it's because the 80s are so far out. I used the SCT preloaded injector slopes for the 80's.
Yes directly to the battery or at least a power source that's hot in both engine run and crank positions so neither your wideband or gauge reset right as it starts or cranking etc.
Yes unfortunately the 80 lb injectors have terrible data to go with them. I spoke to SCT tech support and they gave me some modded settings that helped some but you still have to hack up your MAF transfer curve to compensate for the poor data of the injectors, or maybe it's just the injectors themselves are poor.
On my car on 80s I was pegging the MAF meter around 3/4 throttle in 4th. I switched to ID 1000s and realized how far out of whack my MAF curve was trying to compensate for the 80s and now WOT I'm only hitting around 980 counts.
wow! OK. I got it running by scaling the injector slopes and breakpoint accordingly but it idles like a tank and sounds terrible. AFR is good at around 1000RPM but leans out when I give it gas. It seems to like when I add timing in the borderline knock table but I don't want to add too much.
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