Low fuel pressure for stage 3? 50, dipping to 45

[ritfordprobe]

Let me start off by saying my car runs and drives fine, and holds HOM just fine. I am more confused than anything. I know the stock 2nd gen neon / srt fuel pressure regulator is 58 psi. I was under the impression that the stage 3 comes with a regulator that is higher, maybe 75 psi?

Well, I am getting ready to do my nitrous jetting, so I hooked up a fuel pressure tester to my fuel rail, to see what the fuel pressure is. I primed it a few times, and checked it and it was reading around 60 - 64 psi. Then when I fired it up, it was bouncing between 49 ad 50 as it idled. This immediatly confused me.

I called my buddy over to watch it when I gave it a little bit of gas. I reved it in neutral to 2500, and then to 3000 and he said the pressure dropped down to 45 - 48 psi. This doesn't seem good, it should at least be holding 58 psi, right?

I have stock fuel lines, a walbro 255, stage 3 rail and injectors.

What should my fuel pressure be on a stage 3? Any clue why its dropping when I give it gas?

--mark

[DDogsrt461BLK 3.0]

truth is, that's 100% normal. You'll find that sometimes it may even drop to 40-45psi. The pressure should jump instantly with a flick of the throttle to 55-60psi, even in idle. I've seen my pressure go as high as 80psi under 25+lbs of boost.

[mpbiv]

You're not going to see 75psi at the fuel rail unless the car is under full boost. Remember the fuel rail is demand regulated on Stage 3 cars.

[ritfordprobe]

Quote: Originally Posted by mpbiv

You're not going to see 75psi at the fuel rail unless the car is under full boost. Remember the fuel rail is demand regulated on Stage 3 cars.

Ahhhhh! Ok, that makes total sense then! I was actually nervous when I saw this, but glad to know all is good.

Now the only confusing part will be picking the right fuel jet for my nitrous, since the fuel pressure is variable. Practice will make perfect I bet.

Again, thanks for the information! You settled my mind

--mark

[DDogsrt461BLK 3.0]

Honestly, when I jetted my kit it was for fuel pressure in the 60-75 range. There for, you should be alittle leaner on the fuel jetting then what they ask for. for example

35 shot 31N 16F
50 shot 35N 18F
75 shot 41N 20-22F

I never went any higher........... not yet any ways................

wait til you monkey's see my 4 nozzle......

[ritfordprobe]

I actually have a 35 and an 18 in there now. What are the chances

[DDogsrt461BLK 3.0]

Quote: Originally Posted by ritfordprobe

I actually have a 35 and an 18 in there now. What are the chances

start with a 31N and 16F trust me, then work your way up, it won't take long.

[ritfordprobe]

I'll see if I can track those ones down. If not, it should be OK, but I don't want to risk the motor, I am already making some pretty decent power, as you can see by my trap speed.

You may know, since you seem pretty knowledgeable on this stuff. When I spray, the fuel solenoid is goign to open, and take some of the fuel from the rail (duh, thats how it works ) Will this affect my fuel pressure, in essence having the fuel injectors get less fuel, or will it just work? I figure the regulator will catch any drop in pressure, and make it right.

--mark