Turbo Guru's, I need help!!!! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

PSI240SX · 09-07-2001, 11:21 PM

Okay, just got my KA broken in and started boosting, was at 13psi at first, everything felt perfect with the stock fuel pump. I put in a 300zxTT pump today and drove it and I was getting weird intermittent surging, and what felt to be a loss of power. Back to the shop, pulled the pump out and took the screen off of it and replaced it with the one from the stock pump, thinking it may have been clogged, drove it, same results. Pulled it out again replaced it with a factory Skyline fuel pump, not quite as loud as the 300zx one, same problems but less severe. I tried the boost at 16 psi and even once at 19 psi, still the same thing. And whats weird is after a 40 mile drive to Cocoa, the first three times I floored it, it felt normal, no surging and great power, and after the 40 mile drive home, same thing, normal for the first few full throttles then back to the same surging and loss of power. I have the Jim Wolf ECU and 72 pound injectors, custom fuel rail, and stock fuel pressure regulator with no fuel pressure guage. Gonna try to replace the factory pump tomorrow, (Pain in the ass) and see if it goes back to normal, but until then anyone got any ideas?

*ca18guy* · 09-08-2001, 11:09 AM

Is there a return fuel line on these cars? Maybe you could "clamp" it off alittle and maybe help the fuel pressure. You have alot of money in your car so it would be worth it to buy a fuel pressure gauge, and air/fuel ratio gauge, then start tweeking it. Another thing that popped in my head is the ingnition, maybe your timing, maybe your plugs? These are all just ideas that popped in my head.

PSI240SX · 09-08-2001, 11:55 AM

O.K. boys, I put the stock pump in and it is 100% back to normal, no hesitation, no bucking. I am boosting at 13psi like I was before and the car feels awesome. I am going to get an adjustable fuel pressure regulator, and a fuel pressure guage. Also an EGT guage. When I get all that in, I will let you guys know how it feels

*transient* · 09-08-2001, 09:25 PM

I'm wondering if maybe the 300z pump was pushing so much fuel through that it pushed too much out the return line, and ran lean... Would a standalone fuel management system help that? Course... I don't know what they cost...

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09-07-2001, 11:21 PM	#1
PSI240SX Zilvia Addict Join Date: Jul 2001 Location: The Gunshine State Age: 46 Posts: 843 Trader Rating: (0) Feedback Score: 0 reviews	Okay, just got my KA broken in and started boosting, was at 13psi at first, everything felt perfect with the stock fuel pump. I put in a 300zxTT pump today and drove it and I was getting weird intermittent surging, and what felt to be a loss of power. Back to the shop, pulled the pump out and took the screen off of it and replaced it with the one from the stock pump, thinking it may have been clogged, drove it, same results. Pulled it out again replaced it with a factory Skyline fuel pump, not quite as loud as the 300zx one, same problems but less severe. I tried the boost at 16 psi and even once at 19 psi, still the same thing. And whats weird is after a 40 mile drive to Cocoa, the first three times I floored it, it felt normal, no surging and great power, and after the 40 mile drive home, same thing, normal for the first few full throttles then back to the same surging and loss of power. I have the Jim Wolf ECU and 72 pound injectors, custom fuel rail, and stock fuel pressure regulator with no fuel pressure guage. Gonna try to replace the factory pump tomorrow, (Pain in the ass) and see if it goes back to normal, but until then anyone got any ideas?

09-08-2001, 11:09 AM	#2
ca18guy Premium Member Join Date: Jul 2001 Location: Clearwater FL Age: 39 Posts: 3,226 Trader Rating: (0) Rides Gallery: ca18guy Feedback Score: 0 reviews	Is there a return fuel line on these cars? Maybe you could "clamp" it off alittle and maybe help the fuel pressure. You have alot of money in your car so it would be worth it to buy a fuel pressure gauge, and air/fuel ratio gauge, then start tweeking it. Another thing that popped in my head is the ingnition, maybe your timing, maybe your plugs? These are all just ideas that popped in my head.

09-08-2001, 11:55 AM	#3
PSI240SX Zilvia Addict Join Date: Jul 2001 Location: The Gunshine State Age: 46 Posts: 843 Trader Rating: (0) Feedback Score: 0 reviews	O.K. boys, I put the stock pump in and it is 100% back to normal, no hesitation, no bucking. I am boosting at 13psi like I was before and the car feels awesome. I am going to get an adjustable fuel pressure regulator, and a fuel pressure guage. Also an EGT guage. When I get all that in, I will let you guys know how it feels

09-08-2001, 09:25 PM	#4
transient Premium Member Join Date: Jun 2001 Location: Los Angeles, California Age: 37 Posts: 2,947 Trader Rating: (0) Feedback Score: 0 reviews	I'm wondering if maybe the 300z pump was pushing so much fuel through that it pushed too much out the return line, and ran lean... Would a standalone fuel management system help that? Course... I don't know what they cost...