Why Are My Injectors Hitting 100% Duty Cycle?

[zinkrb250]

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 October 11, 2006 by zinkrb250

[zinkrb250]

anyone?? I'd be glad to answer questions to help diagnose this problem

[R31Nismoid]

You have a walbro fuel pump i bet

*reads sig* Ah... thought as much

Exactly same problem i had

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

[zinkrb250]

You have a walbro fuel pump i bet

*reads sig* Ah... thought as much

Exactly same problem i had

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?

[MBS206]

It just can't deliver the fuel required. Hence injectors open further for more fuel!

[saliya]

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 October 12, 2006 by saliya