I was browsing around under the "Fuel Pump and Pressure Control" settings to get an idea of how I will implement my PWM controller install and noticed there is a setting for "fixed" or "Vac referenced" pressure regulation strategy. It says in the notes that a different calculation will be done internally which makes sense obviously.

Question is with the fuel pump control set to "on/off" I have that particular setting set to vac referenced on a NB which is obviously it is not. If I change this to fixed will this affect the actual fueling calculation or is this purely for fuel pump control?

 

Not in my experience. We tried switching it back and forth with no change in EGO's.

The fueling formula does not include such a correction.

I kind of guessed it came into play with MPG calculations or something that cared about actual flow of fuel through injectors.

 

Cool, I'll change it when the time comes to get the PWM controller working. With that said any concerns with running a walbro 255 with a PWM controller?

I was seeing fuel pressure creep at low loads with it run at full power.