Non-regulated fuel supply question

[SQLGUY]

Hi all,

I'm currently running Microsquirt on a motorcycle with a regulated fuel rail (manifold vacuum based pressure reguator and return line). Recently, when talking with my brother in law about the fuel injection on his Kawasaki ZX10, he mentioned that he has only the high-pressure line coming from the tank - no return line and no vacuum line to set pressure. If this is correct, this would mean that the pressure "seen" by the injectors on his bike (fuel end versus manifold end) would vary with engine load rather than being constant as it is on my bike. So, my question is, is this something that can simply be worked into the VE map? e.g. Smaller numbers at low MAP to compensate for the higher effective pressure across the injector?

Thanks,
Paul

[Matt Cramer]

It probably has some form of regulator unless the pump is a PWM driven setup, just has the regulator not referenced and hidden in the tank.

[SQLGUY]

Hi Matt,

I don't doubt that there's some sort of regulation, but that regulation would appear to be absolute, rather than relative to MAP.

For my setup, 1ms open time will always deliver the same amount of fuel, regardless of engine load.

For the type of setup we're talking about on the ZX10, 1ms would deliver more fuel at low load than at high load. So, I expect, either the required fuel would need to vary depending on MAP (which I don't believe the MS code supports) or the VE map would need to accommodate this. This is what I'm asking about.

Paul

[devastator]

My fuel pressure is only indexed off of the boost pressure, (from the turbo). I use the VE tables to compensate for the steady fuel pressure.

[insanezane]

yeah you can just tune it by lowering the low load areas in the ve table zane

[myk777]

I believe alot of motorcycles don't reference the regulator to the map due to the stability of the map signal on these motors and just make up for it in the fueling tables, take a look at the map signal with a scope it might scare you....