AFPRs

[crimsondragon]

I'm wondering if anybody can explain to me how they work. I'll take anything. Detailed diagrams, pictures, full blown thesis papers, etc etc. How do they compare to stock FPRs and the differences? Why is it we can run without our FPRs but we need AFPRs? What would happen if we didn't have an AFPR but we had a Walbro 255? Does fuel actually go through AFPRs? Did fuel go through our FPRs? Do we need to tune for it? Or can we just set it to the 2g pressure of 43.5psi and everything else will be mechanically controlled? Does the ECU control fuel pressure with the stock FPR?

 

[ilikespeeding]

I'm wondering if anybody can explain to me how they work. I'll take anything. Detailed diagrams, pictures, full blown thesis papers, etc etc. How do they compare to stock FPRs and the differences? Why is it we can run without our FPRs but we need AFPRs? What would happen if we didn't have an AFPR but we had a Walbro 255? Does fuel actually go through AFPRs? Did fuel go through our FPRs? Do we need to tune for it? Or can we just set it to the 2g pressure of 43.5psi and everything else will be mechanically controlled? Does the ECU control fuel pressure with the stock FPR?

Think of them like a small faucet. You control how much water (in this case, fuel) is let out via a screw. With the stock FPR controlling a 255lph, too little fuel exits the rail and causes 70ish psi of fuel pressure under idle...backfires, stalls, flames out the back, etc.

Fuel does go through a fuel pressure regulator. It kind of the same concept of as a boost controller. You're controlling how much vacuum (fuel) is released to get the ideal amount to the actuator (in this case, the injectors).

No, the ECU has no control over fuel pressure. We have a mechanical OEM FPR with vacuum assistance.

 

[Razor_nl]

In the basic situation, a good regulator runs at a set pressure level, and when your boost goes up, the fuel pressure should go up with a 1:1 ratio.
And you can adjust the base fuel pressure to get more fuel in your engine if you want that.

 

[crimsondragon]

Ok so let me get this straight. I want to think of this as a garden hose. The AFPR would be the faucet where we connect the hose to right? Turning the handle controls how much pressure there is. And the garden hose would be the SS line and the fuel rail would be the sprinkler. The injectors would be the openings of the sprinkler which the ECU controls how much goes through. Sounds just about right I believe. Thanks for clearing that up.

 

[ilikespeeding]

Ok so let me get this straight. I want to think of this as a garden hose. The AFPR would be the faucet where we connect the hose to right? Turning the handle controls how much pressure there is. And the garden hose would be the SS line and the fuel rail would be the sprinkler. The injectors would be the openings of the sprinkler which the ECU controls how much goes through. Sounds just about right I believe. Thanks for clearing that up.

Well, that would be backwards. But, correct.

Same situation, take a knife and poke 4 holes in a garden hose. Turn the faucet on full blast. Now, put your finger over the end of the hose. A lot more water came out of those holes right? Your finger is the AFPR.

 

[Razor_nl]

Well, that would be backwards. But, correct.

Same situation, take a knife and poke 4 holes in a garden hose. Turn the faucet on full blast. Now, put your finger over the end of the hose. A lot more water came out of those holes right? Your finger is the AFPR.

That is seriously a nice one to compare it with, I think even my grandma would understand how an AFPR works now