Understanding Return Style Fuel Systems

[Bobby]

That is how I am doing mine.

 

[Flapjack]

Which regulator did you use Flapjack

The 4-port Aeromotive Pro-Series EFI that came with the Lethal kit.

http://www.lethalperformance.com/aeromotive-pro-series-efi-fuel-pressure-regulator-4.html

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[lito]

I couldn't stand the fuel pump running with they key on, so I did install a kill switch and put it in the cup holder (under the cup "spacer", or whatever the hell you call it).

You can keep using the stock FPDM so to power the relay and keep that same feature as before, so it will go on to prime and stop, the thing is that this "priming" is lost and your crank times will be a little longer compared to having the pumps running all the time.

There is also another way by using the FP control lines of the PCM but I have not tested them yet as the FPDM method works great.

If someone wants to use that just need to power the relay coil (Vbat and GND, need to use both, specially the GND) with the pink and black wires that originally went to the stock pump, thru the 85 and 86 relay connectors.

 

[Flapjack]

You can keep using the stock FPDM so to power the relay and keep that same feature as before, so it will go on to prime and stop, the thing is that this "priming" is lost and your crank times will be a little longer compared to having the pumps running all the time.

There is also another way by using the FP control lines of the PCM but I have not tested them yet as the FPDM method works great.

If someone wants to use that just need to power the relay coil (Vbat and GND, need to use both, specially the GND) with the pink and black wires that originally went to the stock pump, thru the 85 and 86 relay connectors.

Those may have been options in the beginning, but the switch works pretty good for me. It also works great for getting fuel out of the tanks and/or lines. Once in a blue moon though, I forget to turn it on.

 

[lito]

Those may have been options in the beginning, but the switch works pretty good for me. It also works great for getting fuel out of the tanks and/or lines. Once in a blue moon though, I forget to turn it on.

Absolutely, I have installed switches myself so I can switch either pump independently but have done this to some customers cars and works great.

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[Flapjack]

Absolutely, I have installed switches myself so I can switch either pump independently but have done this to some customers cars and works great.

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The switch is nice, but it is cool to have so many different options in the tune, too.

 

[05stroker]

You can keep using the stock FPDM so to power the relay and keep that same feature as before, so it will go on to prime and stop, the thing is that this "priming" is lost and your crank times will be a little longer compared to having the pumps running all the time.

There is also another way by using the FP control lines of the PCM but I have not tested them yet as the FPDM method works great.

If someone wants to use that just need to power the relay coil (Vbat and GND, need to use both, specially the GND) with the pink and black wires that originally went to the stock pump, thru the 85 and 86 relay connectors.

so on my setup you would be talking about using the fuel pump control lines from the PCM to activate the relay for the fuel pumps since I no longer have the FPDM?

 

[lito]

so on my setup you would be talking about using the fuel pump control lines from the PCM to activate the relay for the fuel pumps since I no longer have the FPDM?

Yes, if you want your car to be my guinea pig one more time just let me know. As I said, I have not tested but have the idea that this can be done thru that and some changes in the tune. Maybe, we can find that out.

 

[05stroker]

Yes, if you want your car to be my guinea pig one more time just let me know. As I said, I have not tested but have the idea that this can be done thru that and some changes in the tune. Maybe, we can find that out.

Email me the info and I will check it out after I find my current issue on the car. Then we can post our findings after its been tested.

 

[Jared@Lethal]

And here is a 2 port setup run pre rails, not as popular as you have more of a chance for a pressure diffrential the farther away from the regulator you get on the supply side.

That doesn't look safe. LOL

 

[lito]

That doesn't look safe. LOL

Or right, lol.

 

[JeremyH]

lol, not a fan of that method myself either, my buddy has his 2000 gt 2v setup like that with an aeromotive regulator, it works though, at least the gauge by the regulator says it does anyway and he hasnt had an issue yet running 600rwhp... lol

 

[Jared@Lethal]

lol, not a fan of that method myself either, my buddy has his 2000 gt 2v setup like that with an aeromotive regulator, it works though, at least the gauge by the regulator says it does anyway and he hasnt had an issue yet running 600rwhp... lol

Dude must walk around with a rabbit foot in his pocket. Hahahaha.

 

[JeremyH]

Trust me I have urged him to change it on many ocasions even offered to do it for him...

 

[recordbreaker5]

question about the guys who currently run return systems. What do yall see on the Fp gauge while pulling vacuum? I'm trying to determine what my fuel pressure should look like. I see 42psi on the fp gauge at idle pulling 12in of vac. I see that on the rail as well. Should I set my fp to 42psi when at idle or should I see 42psi with 0 vac. My return setup is: hat-3 to 1 y block-filter-1 to 2 y block-rails-fore f2 reg-return line.

 

[jodadejss06gt]

I may have to go to a return setup as I'm getting driveability issues with my huge pumps. Throttle tip in with the pumps cause pressure spikes and it doesn't play nice. The constant pressure of the return may be the way I have to go.

 

[Hawgman]

And here is a "pump to a dead head" method where it dead ends at the rails similiar to the way the new cobrajet is setup. This requires a 4 port regulator.

That is the configuration I am running. I didn't really have much choice with a Mammoth and aftermarket rails unless I wanted to run fuel lines through the firewall

The 4-port Aeromotive Pro-Series EFI
http://www.lethalperformance.com/aeromotive-pro-series-efi-fuel-pressure-regulator-4.html

And I am using that exact regulator

 

[Jared@Lethal]

question about the guys who currently run return systems. What do yall see on the Fp gauge while pulling vacuum? I'm trying to determine what my fuel pressure should look like. I see 42psi on the fp gauge at idle pulling 12in of vac. I see that on the rail as well. Should I set my fp to 42psi when at idle or should I see 42psi with 0 vac. My return setup is: hat-3 to 1 y block-filter-1 to 2 y block-rails-fore f2 reg-return line.

You should set your fuel pressure without the vacuum line installed on the regulator. The other way to do it would be to turn the key to the on position without starting the car with the pumps running. Set the base pressure and tighten the nut on the regulator. Then key the car on and off a few times without starting it just to make sure the gauge at the regulator sees the base fuel pressure you set it at. Once that's been verified you're all set.

Jared

 

[recordbreaker5]

You should set your fuel pressure without the vacuum line installed on the regulator. The other way to do it would be to turn the key to the on position without starting the car with the pumps running. Set the base pressure and tighten the nut on the regulator. Then key the car on and off a few times without starting it just to make sure the gauge at the regulator sees the base fuel pressure you set it at. Once that's been verified you're all set.

Jared

outstanding...now that being said. With my current tune, how will that affect that, or will it since my pressure was higher/lower etc

 

[lito]

You have to talk to your tuner about that, it all depends on what he has done in the tune and how good is the injector data, if you datalog you can use the press drop across injector pid to see your current base fuel pressure without removing a vac line and with the engine running.

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