So my ECU is tuned to 43.5. Stock pressure. Noticed it was actually about 50 psi! ....started adjusting the little screw on the AFPR and couldn't get it to go below 46. Now LOTS of guys running 45 or 46, so I'm not against letting it be and re-tuning for it, however I'm a little concerned that I CAN'T lower it if I wanted to.

Details: BBK AFPR has been used at 43.5 for years, and without removing from the rails, is now on my new 383. I do have a new Racetronix 255 pump, but I can't see that pushing it THAT high that I can't go any lower. LOTS of guys running 255's and I've never heard of this issue.

Thoughts? Not really worried....but it's nagging at me

 

The Adjustable Fuel Pressure Regulator should be adjusted with motor running and
regulator vacuum line disconnected. The ecm doesn't care if your at 3bar. But increasing pressure increases injector #hr flow.

 

Yes, the car was running and vacuum was disconnected. Started at 50, dropped to 46. ....with vacuum, at idle it's about 38/39. ....and I adjusted the fuel accordingly in the tune to 46psi (was at 43.5) How much of a difference will it make, I don't know. Is 2.5pSi insignificant, or HUGE!? I don't know, but just to be safe I adjusted the #per hour/actual pressure in the tune.
My issue is more WHY can I not drop it lower than 46?

 

2.5psi increase is about .4 #hr increase. That's a odd one that you can't lower it down any more.

 

Sure the psi gauge is working properly?

 

Agreed. ...not worried about the 46 per se, worried that I can't lower it IF I wanted to.

Anything is possible, but I have two gauges on it. A fixed gauge on the rail itself, and the ECU itself. Both read the same.

 

The return line may be kinked or dented. Also, back at the tank to frame lines, double check that the return line from the frame goes to the tanks return. Not the tanks vent line (CCP vent).

RBob.

 

Speaking about kink in the return line. I have only seen this once but the inner layer of a fuel line came free causing a huge restriction. Rare example I'm sure

 

Pretty sure I hooked up the lines properly, but of course, I'll have to check to be sure. ....as for the line being kinked, or possible something restricting inside....obviously it's possible, but it worked just fine when it came off the road. ....but yes, I understand anything is certainly possible. I'm gonna move forward with tuning, however I'm also gonna dig into this a little. If for no other reason than piece of mind.

Thanks guys