AFPR Malfunction Question

[Saul325is]

Ok, so I basically installed a fuel pressure gauge, and the gauge read 37.5psi with stock FPR, then I installed an AFPR, adjusted it to 37.5psi, and after a drive my fuel pressure reads 25psi, sometimes it reads 60psi also. Do I just have a fautly AFPR? It's a bav auto AFPR by the way.

-Saul

[Jordan]

Are you using BavAutos rising rate FPR?

[Saul325is]

I have no clue, is that the adjustable one?

[Jordan]

I have no clue, is that the adjustable one?

No.

Is your stand alone, or does it mount entirely to the fuel rail?

[Saul325is]

it mounts where the stock FPR mounts, dirrectly bolt on..

-Saul

[DaN]

Where are you measuring fuel pressure?
You have the vacuum line connected right?
You know fuel pressure is supposed to rise when you give it gas, or lose vacuum, right?
Have you checked for leaks?

[DaN]

Is this what you have?

"Get more power and better throttle response from your BMW. This adjustable rising rate fuel pressure regulator enriches the fuel mixture as you accelerate to increase power and improve mid-range throttle response. Maintains stock fuel mixtures at idle."

[Saul325is]

I'm measuring my pressure through a pressure gauged that I had tapped in after the regulator. I have checked for leaks, none. I do know that the pressure rises when I apply gas. But the thing is, It fluctuates at idle somtimes. I mean when I start my car when its cold, it takes a while to get up to the pressure that I had set. And after I do like a 30 minute drive, I open my hood and sometimes it reads 50psi, and sometimes 25psi, when I had allready set my AFPR to 37.5psi. It's not the guage, because when I had my stock FPR and tapped in my gauge, ti read 37.5 psi like normal. From what I have heard, there might be a leak in my vaccuum line?

And yes, that is the AFPR that I have above...

Thanks,
Saul

[Jordan]

And yes, that is the AFPR that I have above...

Last I check, that isnt not a AFPR, it is just a RIsing Rate FPR.

From what you said it is working as intended, but its owner is just dumb.

[Saul325is]

And yes, that is the AFPR that I have above...

Last I check, that isnt not a AFPR, it is just a RIsing Rate FPR.

From what you said it is working as intended, but its owner is just dumb.

No, it IS an AFPR, its a rising rate AFPR. Hell, if I can adjust it its an AFPR, which I can.

[Jordan]

look, that is not an adjustable FPR. it is just a rising rate fpr with idle adjustability. as you said eariler, you have no clue.

it is working as intended.

[JRowe]

The problem is the location of your fuel pressure gauge. You need to measure before the regulator. By placing the gauge after the regulator, you're basically measuring the fuel pressure in the return line, not the fuel pressure at the injectors. Also, your fpr is a rising rate fpr with an adjustable initial setting.

[Saul325is]

The problem is the location of your fuel pressure gauge. You need to measure before the regulator. By placing the gauge after the regulator, you're basically measuring the fuel pressure in the return line, not the fuel pressure at the injectors. Also, your fpr is a rising rate fpr with an adjustable initial setting.

Thank you, so true....The location of the gauge is allright, because when I did have my stock FPR, it read 37.5psi like normal...Overall I found out that there is a very minor leak in my vaccuum line to the rising rate afpr, thats what is causing the problem sometimes. Thanks for your help guys...

-Saul

[DaN]

The problem is the location of your fuel pressure gauge. You need to measure before the regulator. By placing the gauge after the regulator, you're basically measuring the fuel pressure in the return line, not the fuel pressure at the injectors. Also, your fpr is a rising rate fpr with an adjustable initial setting.

Thank you, so true....The location of the gauge is allright, because when I did have my stock FPR, it read 37.5psi like normal...Overall I found out that there is a very minor leak in my vaccuum line to the rising rate afpr, thats what is causing the problem sometimes. Thanks for your help guys...

-Saul

No, the location of the gauge is not alright, if you know how a fuel injection system works you'll realize that the pressure before and in the fuel rail is regulated.

If you install the gauge on the return line coming off the regulator, you are just measuring the pressure of whatever the regulator dumps to maintain correct pressure in the rail.

So install your guage in one of the lines coming into the fuel rail, near the fire walll.
You will probably find that your pressure is way out of wack.

[Saul325is]

The problem is the location of your fuel pressure gauge. You need to measure before the regulator. By placing the gauge after the regulator, you're basically measuring the fuel pressure in the return line, not the fuel pressure at the injectors. Also, your fpr is a rising rate fpr with an adjustable initial setting.

Thank you, so true....The location of the gauge is allright, because when I did have my stock FPR, it read 37.5psi like normal...Overall I found out that there is a very minor leak in my vaccuum line to the rising rate afpr, thats what is causing the problem sometimes. Thanks for your help guys...

-Saul

No, the location of the gauge is not alright, if you know how a fuel injection system works you'll realize that the pressure before and in the fuel rail is regulated.

If you install the gauge on the return line coming off the regulator, you are just measuring the pressure of whatever the regulator dumps to maintain correct pressure in the rail.

So install your guage in one of the lines coming into the fuel rail, near the fire walll.
You will probably find that your pressure is way out of wack.

Nah, the guage is installed right, it is on one of the lines comming into the fuel rail. I just got confused from the different areas where fuel is being let in and let out.. Sorry.

-Saul