Japtastic141

Ok, will keep it fairly short but essentially I had multiple issues.
The original old fuel pump and FPR were well past their best.
The replacement 450lph Walbro was overpowered for my setup and wiring.
Wiring was replaced but the problems persisted.
Out-of-sight fuel hose was leaking but seemed to be only under high load and not at idle even with the Mytivac bringing fuel pressure up to 5Bar.
Once the fuel hose was replaced, the fuel pump swapped to a 255lph Walbro and FPR replaced, the problem was essentially fixed.
What skewed the results after everything was fixed was that the Tomei FPR has a very bad regulation slope. @Adamw Said the typical slope is around 0.25kpa / LPH.
Tomei Type S (and probably the Type L) = 0.43kpa / LPH which equates to a 47kpa loss at the high rev range. This matches what I found online and my own logs.
Turbosmart FPR6 (and their other models) = 0.16kpa / LPH which equates to a 10kpa loss at the high rev range. Which again matches very closely to my logs now.
I hope someday this whole thread is useful to someone in the same situation. Got to say a big thanks to everyone who helped as well. I've learnt a huge amount. Really appreciate it.
Now back to tuning the car which is a lot more fun than troubleshooting this! 

Ok, will keep it fairly short but essentially I had multiple issues.
The original old fuel pump and FPR were well past their best.
The replacement 450lph Walbro was overpowered for my setup and wiring.
Wiring was replaced but the problems persisted.
Out-of-sight fuel hose was leaking but seemed to be only under high load and not at idle even with the Mytivac bringing fuel pressure up to 5Bar.
Once the fuel hose was replaced, the fuel pump swapped to a 255lph Walbro and FPR replaced, the problem was essentially fixed.
What skewed the results after everything was fixed was that the Tomei FPR has a very bad regulation slope. @Adamw Said the typical slope is around 0.25kpa / LPH.
Tomei Type S (and probably the Type L) = 0.43kpa / LPH which equates to a 47kpa loss at the high rev range. This matches what I found online and my own logs.
Turbosmart FPR6 (and their other models) = 0.16kpa / LPH which equates to a 10kpa loss at the high rev range. Which again matches very closely to my logs now.
I hope someday this whole thread is useful to someone in the same situation. Got to say a big thanks to everyone who helped as well. I've learnt a huge amount. Really appreciate it.
Now back to tuning the car which is a lot more fun than troubleshooting this! 

Ok, will keep it fairly short but essentially I had multiple issues.
The original old fuel pump and FPR were well past their best.
The replacement 450lph Walbro was overpowered for my setup and wiring.
Wiring was replaced but the problems persisted.
Out-of-sight fuel hose was leaking but seemed to be only under high load and not at idle even with the Mytivac bringing fuel pressure up to 5Bar.
Once the fuel hose was replaced, the fuel pump swapped to a 255lph Walbro and FPR replaced, the problem was essentially fixed.
What skewed the results after everything was fixed was that the Tomei FPR has a very bad regulation slope. @Adamw Said the typical slope is around 0.25kpa / LPH.
Tomei Type S (and probably the Type L) = 0.43kpa / LPH which equates to a 47kpa loss at the high rev range. This matches what I found online and my own logs.
Turbosmart FPR6 (and their other models) = 0.16kpa / LPH which equates to a 10kpa loss at the high rev range. Which again matches very closely to my logs now.
I hope someday this whole thread is useful to someone in the same situation. Got to say a big thanks to everyone who helped as well. I've learnt a huge amount. Really appreciate it.
Now back to tuning the car which is a lot more fun than troubleshooting this! 

Ok, will keep it fairly short but essentially I had multiple issues.
The original old fuel pump and FPR were well past their best.
The replacement 450lph Walbro was overpowered for my setup and wiring.
Wiring was replaced but the problems persisted.
Out-of-sight fuel hose was leaking but seemed to be only under high load and not at idle even with the Mytivac bringing fuel pressure up to 5Bar.
Once the fuel hose was replaced, the fuel pump swapped to a 255lph Walbro and FPR replaced, the problem was essentially fixed.
What skewed the results after everything was fixed was that the Tomei FPR has a very bad regulation slope. @Adamw Said the typical slope is around 0.25kpa / LPH.
Tomei Type S (and probably the Type L) = 0.43kpa / LPH which equates to a 47kpa loss at the high rev range. This matches what I found online and my own logs.
Turbosmart FPR6 (and their other models) = 0.16kpa / LPH which equates to a 10kpa loss at the high rev range. Which again matches very closely to my logs now.
I hope someday this whole thread is useful to someone in the same situation. Got to say a big thanks to everyone who helped as well. I've learnt a huge amount. Really appreciate it.
Now back to tuning the car which is a lot more fun than troubleshooting this! 

I'll update this later properly but swapping the Tomei Type S FPR to a Turbosmart FPR6 has fixed the problem of dropping such a big amount. It wasn't the only problem as I'll update later.
The spikes now down only happen when I let the throttle off as you can see then it's back to normal. 296kpa is reported as a baseline so now only dropping 10-12kpa at a maximum while on 1 bar of boost and 7k RPM! Well happy!

Biggest is best for fuel pump control

cold/warmup idle 300°C, warm idle 450-500°C as the exhaust is still warm from the previous running