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Fuel pressure too low


Guest mck2

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Guest mck2

I have an intercooled 1983 turbo engine in a 240Z. 240Z fuel lines. custom fuel rail. Stock 280cc injectors, 1983 fuel pump and pressure regulator. 1/2Volt drop at the pump. Max observed fuel pressure is 43psi at 12psi boost. Base pressure at idle with vac hose off reg is 38psi. So we need 38+12=50psi? Dyno indicates too lean above 4500 rpm. Do I need a better pump or a rising rate pressure regulator??? Give model numbers if possible. Might use 370cc someday.

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It sounds to me like you have a failing pump. If it were a simple line restriction, your base pressure would be off as well. I wouldn't run 12 psi boost often with that drop in pressure. At the very least, replace the pump with a high pressure Bosch pump, the stock one will not flow well over 12-14 psi boost anyway.

 

I just installed a new CIS Bosch pump for a 77-79 Porsche 911, and it's working well with 15 psi boost.

 

Opinion: RRFPR is not right for AFM or MAF systems. It works better for Hondas and other EFI systems that use 1 bar MAP sensors.

HTH

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It is possible that the stock pump can't keep up as well. I say... new fuel pump. Walbro GSL-392 is the unit I am using with a 43psi base and no pressure drop (63psi) at 20+ lbs of boost.

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