Fuel Pressure slightly too high an issue?

[Rob Furniss]

I fitted a fuel pressure regulator a few weeks back, it has dual inlets and a return so I've now split the fuel rails and got two feeds in and two out to the FPR.
Issue is this regulator won't adjust below 42psi, it will go up but not below this and stock pressure is supposed to be 38psi I believe, so is this an issue or not really?
The car is running slightly rich at idle sometimes, i'm suspecting a leaky injector and have checked the front ones already so will be moving onto the rear bank when I have time to take the supercharger and charge cooler off but i'm thinking the increase in pressure won't be helping either. When I turn the engine off the pressure drops right down within a few seconds which is making me think leaky injector.

[spetz]

Did you measure the pressure with the vacuum hose disconnected?

I ended up stupidly setting my FPR are 42psi without the vacuum hose disconnected.
So the "real" pressure was about 60 something psi.
Ran fine but rich.

[Rob Furniss]

Just checked again, it's about 44psi with vac hose connected and 56psi disconnected.
I also disconnected the intake temp sensor connector and then reconnected it, didn't make any difference to how it was running although the engine light came on when I disconnected - fine now I put it back.
AFR has been spot on though this morning fluctuating between about 14.4 and 15, I did swap out an injector on the front bank the other day when checking them as it looked like it had a slight leak so wondering if that has helped a bit.

I noticed a review that someone did on these FPR's (an almost identical one to mine, different seller) and he said his was working great but couldn't get base pressure below 44psi, so i'm thinking it must be inherent in the design and not my setup.

I know 44psi is a little higher than standard but is it ok?

[Vectose]

Won't be an issue if you correct it in the fueling. Increasing pressure is a quick and easy way to get more flow from injectors as long as the injectors are rated for that pressure.

GM for instance run 58psi base pressure.

Base pressure should be set with the pump running but engine off.

[Rob Furniss]

Thanks Rob, and Oh sh*t I set it with the engine running.
Is there an option to run the pump through evoscan as I recently got that and the cable but haven't been into it much yet (I've had it communicate with the car though) or do I need to hot wire the pump?

if I can get it to 40psi with the pump running but engine off that would be a good base pressure?

And looks like I got it all wrong about CDH275 injectors (what I have) which I thought flowed at 275cc, I've found a few sources saying the flow is 318cc at 3 bar fuel pressure.
In the emanage injector sizing I put in 166cc for before and 275cc for after change, now not sure whether I need to change this.
It looks like at 44psi they would flow at up to 318cc but when wide open throttle the pressure be increased to around 56psi so they could be like 360cc?

The car isn't running bad so maybe I should leave it alone

[Rob Furniss]

Just been for a little drive and it's behaving itself, good AFR.

[spetz]

From my understanding the base pressure is set with the engine running however the vacuum hose disconnected from the FPR

[Vectose]

From my understanding the base pressure is set with the engine running however the vacuum hose disconnected from the FPR

Yeah, because that's the easiest way to do it, rather than powering the pump on its own. There really won't be any noticeable difference but ideal way is engine off without injectors firing.

[Rob Furniss]

I've replaced the FPR with an Aeroflow model.
Checked/set fuel pressure and something is odd as it's the opposite to what's in the manual as mine is higher when the vac hose is disconnected (now this is what I would have expected anyway as if connected and pulling vac then it means the BF closed so we don't want higher pressure, we want higher pressure when what so no vac i.e disconnected vac hose simulates this)

Manual says 265kpa disconnected which is 38.4psi, and 324-343 with vac hose connected (47-50psi)
has the manual got it the wrong way round or have I, or do I have a crap gauge?
My pressure is reading 38psi vac connected and engine running, idle, BF valve closed.