: Fuel Induction System Specs



Ekindler0584
06-24-08, 05:30 PM
For an '01 Seville, does anyone have the specs on the fuel pressure regulator, and fuel injectors. Specifically, the operating pressure range of the injectors, and (although it may be wishful thinking)... a chart showing the "vacuum pressure vs. fuel pressure" of the regulator.


Thank You,
Edward S Kindler

Submariner409
06-24-08, 06:47 PM
Fuel pressure is fairly constant and the return rate is controlled by the regulator depending on manifold vacuum while injector rate and pulse width is controlled by the PCM and sensor inputs.

The FSM gives precious little info.

Hook up a manifold vacuum and fuel pressure gauge on a suction cup mount on the hood and DIY.

(Some have already tried fuel rate modification with little success.) AJ works with it when adjusting his Fiero nitrous system.

AJxtcman
06-24-08, 10:54 PM
(Some have already tried fuel rate modification with little success.) AJ works with it when adjusting his Fiero nitrous system.

The Nitrous is on the DHS

eldorado1
06-24-08, 11:30 PM
The FPR reacts to changes in manifold vacuum to keep the injector flow linear. When idling, there is a vacuum in the manifold, and it works to pull fuel from the fuel injectors. Since this would increase the amount of fuel delivered to the engine, fuel pressure is reduced when manifold vacuum increases, and vice versa.

At wide open throttle, you might see 95kpa. At idle, you might see 30kpa. The difference works out to be about 9psi. So if the fuel pressure regulator is linear, you'll see it go from _something_ to _something+9_

In my experience, cadillac injectors can't handle much overpressure. They seem to start closing around 55-60psi. You wouldn't want to run an injector lower than 40psi. Keep in mind the flow rate changes with fuel pressure.

AJxtcman
06-25-08, 07:49 PM
I have run the Fuel pressure up to 60 PSI with no problem on 95 to 99 engines, but you have a plastic fuel rail that can break. I have added 10% to 20% (5 to 10 psi) over stock and that seem about the best. Stock Fuel Pressure is 41 to 47 static.

On 2000 to 2005 I have found the injectors locking above 20% increase (about 55psi @ 0" of vacuum). The car will actually lean out.

We found a slight 3 or 4 PSI increase on this car will set the fuel trim on the minus side and produce more power, but we need this for Nitrous. I don't think anyone would see a gain.

eldorado1
06-25-08, 10:48 PM
On 2000 to 2005 I have found the injectors locking above 20% increase (about 55psi @ 0" of vacuum). The car will actually lean out.

Found same problem on 95 and 96 injectors. They just snap shut and don't open anymore. Coil doesn't seem able to lift the pintle.