SC400 Max Fuel Pressure (help please!)
 

I have a sc400 with 1jz single swap. Stock sc400 fuel pump, stock lines, AEM FPR, 440cc injectors (750s and rail waiting to go in :D ), big 70mm turbo.

I need to know what is the max fuel pressure that a healthy stock sc400 fuel system can put out?

I am having leaning issues starting around 7-8psi. I have already tried adjusting fuel map all the way up at those datum points. I just don't think I am supplying enough fuel. BUT, I have had the car for 4 months now, and haven't had these issues. I am wondering if my fuel pump and/or filter are going bad. Although, previous owner supposedly put brand new pump in shortly before I picked it up.

The MOST I can adjust the FPR up to is 38PSI (with vacuum connected). I seem to think before when I first started tuning it, that I was able to adjust it much more than that.

Please guys, give me some numbers if you know them and thanks.

anyone know? Thanks

I don't know the answer, but I'm pretty sure I've seen 38-44 psi listed as the typical range. (Not sure if that's just the 1UZ or also the JZ variants.) That would indicate you're too low if 38 is your max adjustable.

Thanks bud. I came across a page in the manual that says that with vacuum disconnected, expect 38-44psi. With vacuum connected, expect 28-34psi. So, I guess the pump is putting out what it's supposed to. I will have to see what happens when I put in the larger injectors. Might have to go to a walbro.

If you can only get 38psi out of your adjustable pressure regulator then you have a leak somewhere or the diaphragm is going bad

This problem ended up being the fuel pump. Previous owner had a stock SC400 pump installed, which apparently got lazy. I also changed the fuel filter. The old filter had much more restriction while blowing through it than the new one. That however, did little to help the situation. Once I installed an Aeromotive 340 stealth, the leaning issues went away, and I was able to adjust fuel pressure to at least 60 psi (didn't try to go anymore but could've). Thanks guys