Does anyone have a diagram showing how an FPR works? (corbin?) I am curious as to how these things work. I can hook them up but I dont know whats going on inside of them.

Here is it:



That is more like an HRC FPR. The S-FMU is a little more complex. Air pressure pushes on one side of the diaphram (trying to close the valve) and gasoline pressure pushes on the other side of the diaphram (trying to open the valve). Opening the valve allows gasoline to return to the gas tank. Gasoline will not make it past the FPR unless it has reached the fuel pressure that you set with the adjustment screw (and air pressure). This creates a certain pressure before the FPR (in the fuel rail/injectors). I don't think I left out any major parts, but I did make this diagram off the top of my head...

Corbin

'95 ESI-T
HRC+FMIC+ETC...

excuse me for the stupido questions but what do FPR and s-fmu mean? tryin to increse knowledge here help me out thnx


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Fuel Pressure Regulator. and the s-fmu is the same thing. Thanks corbin!!!!!!! I knew you could enlighten me with your turbo knowledge.

Wow, that diagram rocks corbin, thanks!

Except... now I don't understand
- why my fuel pump is hella loud at IDLE, and quiet at boost.
- why the pump gets QUIETER as the idle fuel pressure INCREASES

Until now, I thought the pump got louder because it had resistance (trying to pump fuel against a closed valve). But when the fuel started getting eaten up quick, (or returned to the gas tank easier) the pump didn't have to push so hard and therefore was quieter...

Question 1)
Closing the valve (increasing FP) causes more fuel to get returned?

Question 2)
Can I assume the FP is quieter when it is working hard (high boost, high static FP)

Question 3)
What's the check valve for? If the fitting is for air IN, where does the air pressure come from, atmosphere?

Huge tia,
Dan

>Question 1)
>Closing the valve (increasing FP) causes more fuel to get
>returned?

You can assume that more fuel gets returned at low pressure. Very little fuel is used to run the engine at idle/cruise (low pressure). The engine uses more fuel at higher pressures, so less would be returned to the gas tank.

>
>Question 2)
>Can I assume the FP is quieter when it is working hard (high
>boost, high static FP)

The pump may be quieter because it is spinning slower at higher pressures. That is why is flows less fuel at higher pressures. There is probably so much other noise in the car while boosting, that you don't notice the pump as much.

>Question 3)
>What's the check valve for? If the fitting is for air IN,
>where does the air pressure come from, atmosphere?

I wanted to keep it simple, so I didn't put the bleed valve and check valve in. The bleed valve, does what you'd think. It bleeds off some of the air in the upper cavity of the FPR. This means that the upper cavity will have a lower pressure (and fuel pressure will drop). The check valve goes on the end of the bleed valve to make sure that no air leaks INTO the FPR from the atmosphere. This is only possible when the engine is operating under vacuum (idle/light cruise). If I ever make a web page for FPR info, I'll add some more details to the diagram. Nobody's really asked for details of FPR guts until now.

Corbin

'95 ESI-T
HRC+FMIC+ETC...