Have you made the change I suggested in your other thread yet?
With the vac/boost line to the fuel pressure regulator disconnected it should be 52psi. The vac/boost line adjusts it down or up by how much vacuum or boost is in the intake. For example, the fuel pressure should be at 56psi if you are making 4 psi of boost. 45psi at idle is normal.
With the 3800SC you MUST use a 2 or 3 BAR fuel pressure regulator. Fuel pressure needs to rise to boost pressure plus the base number of 43-45psi . In other words at 10 psi of boost you should have 53-55 PSI of fuel pressure. If you don't see that fuel pressure at boost, the engine will encounter a lean condition that can blow a piston.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 08-25-2017).]
The question to be asked is the fuel pressure rising with the boost? That is why its important to run both a fuel pressure gauge and a boost gauge. As for BAR; that's barometric/atmospheric pressure of 14.7 psi. A 2 BAR fuel pressure regulator is referenced to 1 BAR level and provides 43-45 psifuel pressure at idle and a rising rate of fuel pressure as boost increases to a 2 or 3 BAR level. In simple terms your fuel pressure must equal base fuel pressure + boost pressure. If it is not either the vacuum line is obstructed/leaking, the regulator is defective or you have a leak in the tank line which connects the fuel pump to the fuel line. Take the car for a drive and measure the fuel pressure as you hit the pedal hard. If the fuel pressure increases the regulator is probably good.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
oK. now I understand what you're saying. but Why would the factory have connected the "Fuel pressure Line" to the "Upper tree" on the Supercharger and not the port at the front of the manifold where the Map sensor is routed ?? Thanks
Originally posted by Lou6t4gto:but Why would the factory have connected the "Fuel pressure Line" to the "Upper tree" on the Supercharger and not the port at the front of the manifold where the Map sensor is routed ??
They didn't.
This is the factory routing:
Edit: Some older superchargers had a side vacuum/boost tree which is shown on a lot of diagrams. On those cars that is where the fuel pressure regulator attached. That's probably where the confusion came from.
[This message has been edited by Domtech (edited 08-30-2017).]
