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Why Are My Injectors Hitting 100% Duty Cycle?

zinkrb250

By zinkrb250,
in Engines & Forced Induction

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zinkrb250 Enthusiast

zinkrb250

Posted
Posted (edited)

SII rb25det

-using power FC-

Can't figure out why my nismo 555cc injectors are hitting 100% duty cycle when i'm only making 371horsepower... any ideas???

-Duty cycle is set at 66.5% at .14m/s lag

-Fuel pressure is set at 43psi w/o vacuum

-Brand new fuel filter

Edited by zinkrb250
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

You have a walbro fuel pump i bet

*reads sig* Ah... thought as much

Exactly same problem i had :P

throw it in the bin, or get a surge tank and use it as a lift pump... about all they are good for.

zinkrb250 Enthusiast

zinkrb250

Posted
  • Author
Posted
You have a walbro fuel pump i bet

*reads sig* Ah... thought as much

Exactly same problem i had :P

throw it in the bin, or get a surge tank and use it as a lift pump... about all they are good for.

So you were using a walbro fuel pump and reading 100% duty cycle?... I don't understand how a failing fuel pump would make the powerfc read 100% duty cycle... could you please explain?

saliya Rising Star

saliya

Posted
Posted (edited)

Hey,

put a fuel pressure gauge on your supply line and see if your pump's running out of flow (you will see fuel pressure follow

boost initially, then fall off _before_ boost if the pump runs out of flow).

If you can borrow one, this will tell you a) straight away and b) cheaply if your fuel pump is the culprit.

edit: of course, you need to do this on a dyno or on the road (you're interested in fuel pressure at high rates of flow,

not at idle).

Regards,

Saliya

Edited by saliya

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