Manifold Vacuum Multiplier: [ECM] 6950

[CCS86]

For a return style fuel system, I assume the description is correct here and it should be zeroed out:

[ECM] 6950 - Manifold Vacuum Multiplier: This parameter is used to scale inHG to PSI, or to disable manifold vacuum comp. Set to 0 if going to a return style.

Are there any other parameters specific to a return style system (besides all the inferred rail pressure tables and injector pressure multipliers)?

[murfie]

Diagnostic test, monitors, voltage control loops and duty cycles... With out the FPDM needing to control the pump speed to produce a desired pressure, they can be disabled and ignored.

You want pump on full, and the regulator controlling pressure, for simplicity.

The multipliers as 1's,and inffered rail pressure set to a constant pressure isn't reality with a 1:1, but it does the trick of you basically having a single injector flow rate, for the most part.
If you are not using a 1:1, you want the pump on full, and the regulator controlling pressure. Inffered pressue to the set PSI, and the flow multipliers working for the injectors and that vaccum multiplier. You are basically just taking away the FPDM and pump speed control.

[Witt]

For a return style fuel system, I assume the description is correct here and it should be zeroed out:

[ECM] 6950 - Manifold Vacuum Multiplier: This parameter is used to scale inHG to PSI, or to disable manifold vacuum comp. Set to 0 if going to a return style.

Are there any other parameters specific to a return style system (besides all the inferred rail pressure tables and injector pressure multipliers)?

If you zero out the manifold vacuum multiplier, you can keep the injector data as returnless, no need to set the pressure multipliers to 1 and calculate the flow rate for a set pressure. You do have to set rail pressure table to your base pressure.

I've been doing this since the vacuum multiplier was defined. Keeps me from having to recalculate the injector flow rates if I have to change pressure, instead just have to change the rail pressure table. It's exactly how Ford sets it up in their crate tunes.