Timing of ECU settling and initial start up idle speed

[rfinkle2]

Tokay, I think it is the spill valve solenoid that you are talking about.

I know that controls the ultimate pump pressure via valve and solenoid.

[Ziggo]

Even if you only run for a couple seconds, remember that the injectors go right into the cylinder and will conduct heat from the cylinder back through the injector into the fuel. As to how much heat, and how much pressure rise it causes, that's a big science project that I don't have much interest in.

The CDFP stops when the engine does. There is a free spinning period when the engine slows down after it has been turned off where the CDFP would continue to pump with the injectors off, but I doubt the solenoid would be open to feed fuel into the pump then anyway. Once rpm = zero the CDFP will not generate any extra pressure.

Pressure rises require energy. If the pump isn't spinning, the energy is coming from elsewhere and in this case my bet is latent heat. When the motor is running and the injectors are flowing the fuel stays cooler as fresh fuel flows in, when the flow stops the fuel in the rail will heat up.

On some systems this can result in vapor lock as the fuel gets hot enough to vaporize and stall the feed pump. Then you won't be able to hot start your vehicle.


Zigatapatalka

[Tokay444]

No one is trying to say it generates any pressure when you then the car off.
I'm saying it bleeds of the pressure it has stored before its turned off.
The pump itself is either on or off. Meaning its either making maximum pressure, or no pressure at all. So when you shut the car off, the pump has a stored pressure somewhere north of 1600psi.
That pressure then bleeds off into the rail where the sensor is, causing the sensor to register a rising rail pressure with the engine off.

[Ziggo]

There is no chamber of stored pressure. It is just a simple piston with a check valve at the end. When the piston is compressing and the chamber pressure is higher than the rail the check valve opens and fuel flows past.


Zigatapatalka

[Tokay444]

I need to have a better look at the system.

[rfinkle2]

This may help... This diagram is courtesy of one of Enki's threads on e85...

The diagram may / may not be supplied by him as well: