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TBatt · 06-24-2016, 10:38 AM

According to what I have read about the Walbro 255, it is a Genrotor type pump, which is a positive displacement pump and it should run all of the time letting the regulator bypass what is not needed to maintain ~55psi. The ECU starts the pump for a few seconds and then turns it off until the engine starts to turn over. This way the pump doesn't get overloaded when it doesn't need to run. This is what it is doing, coming on and then shutting off until the engine starts. So, the electronics seems to be working but the pump is not developing pressure any more. That could be the pump or the regulator. I'm waiting on a call from Stillen to see what there tech guys says.

When I first installed the new pump (part of the Stillen SC kit) the fuel pressure was around 55psi and has now dropped to 10. The engine will run but the car is not drive-able. The idle AFR was 14.4 and now it is in the 16s which is way lean due to the low fuel pressure.

I'll keep you posted on what I find.

06-24-2016, 10:38 AM	#4 (permalink)
TBatt Track Member Join Date: Apr 2013 Location: Huntsville, AL Posts: 832 Drives: 2019 GT-R Rep Power: 20168	According to what I have read about the Walbro 255, it is a Genrotor type pump, which is a positive displacement pump and it should run all of the time letting the regulator bypass what is not needed to maintain ~55psi. The ECU starts the pump for a few seconds and then turns it off until the engine starts to turn over. This way the pump doesn't get overloaded when it doesn't need to run. This is what it is doing, coming on and then shutting off until the engine starts. So, the electronics seems to be working but the pump is not developing pressure any more. That could be the pump or the regulator. I'm waiting on a call from Stillen to see what there tech guys says. When I first installed the new pump (part of the Stillen SC kit) the fuel pressure was around 55psi and has now dropped to 10. The engine will run but the car is not drive-able. The idle AFR was 14.4 and now it is in the 16s which is way lean due to the low fuel pressure. I'll keep you posted on what I find. __________________ RJM pedal, Hotchkis Sway Bars, FI TDX, FOG Light, Z1 Slotted Drilled rotors, Stillen SC, Quaife ATB, Z1 Oil cooler, AEM Gauge Set, Galeforce gauge mount, Avant Garde M590 Hypersilver w/RE-11, TopgunZ A2A kit., ECUtek tuned by Seb: ROLL TIDE! Last edited by TBatt; 06-24-2016 at 10:43 AM.