fuel pressure - Performance Forum

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fuel pressure
Tuesday, October 10, 2006 9:36 PM
Just a heads up-I don't have a wideband yet and no o2 sensor after the cat right now (will pick it up tomorrow). I think the o2 sensor may be the problem, but here is my dilema.

Is stock fuel pressure supposed to be 43 psi at idle or wot?

I have the fuel pressure at 40 psi at idle, and when I open the throttle, it shoots up to 50 psi. I know our cars naturally run rich at wot (even though it was about 1/2 throttle), but does that sound normal. I would think fuel pressure would drop, if change at all, as the injectors open more often at higher rpms and therefore flow more fuel.

Oh yeah, the fuel is 93 octane and has been sitting in the tank since the motor went in December (I really don't think that matters, but thought I'd share in case for some reason it should).

Re: fuel pressure
Tuesday, October 10, 2006 9:51 PM
your fuel pressure is supposed to raise as you open up the throttle..... that sounds about right for pressures.... you need more pressure at wot to supply more fuel.
that is what the fuel pressure regulator is for. at idle you have alot of vacuum to it and allows more fuel to return to tank, but when you open throttle the vacuum is less and the fpr restricts the flow back to the tank thus inturn raises pressure
Re: fuel pressure
Tuesday, October 10, 2006 10:03 PM
Thanks for clearing that up for me justin...that makes plenty of sense. Now I just need a wideband to see how rich the car is running.
Re: fuel pressure
Tuesday, October 10, 2006 10:07 PM
no problem
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