Trying to diagnose what I think is a bad fuel pump (since I obtained nearly the same fuel flow with and without a filter.

I measured it at almost exactly 45 gallons per hour.
Is this correct for the stock 94 fuel pump? what is the stock gph rating of the fuel pump?

at 6.3 lbs of gas per gallon, that's 283.5 pph
I see "high volume pumps" running at 450 pph, which is about 72 gph.

End questions are really....I'm suffering fuel loss at WOT, and its getting progressively worse, injectors are clean and running fine, everything is fine except for WOT at higher RPM, injectors are not going past 80% duty cycle.

To me that leaves fuel pump, and fuel filter...but if 45gph(283.5pph) stock is what its supposed to be flowing, and its doing fine....then what is the problem.... if its not, then I'll finally upgrade my fuel pump and be out $300

 

well, page 8 of a search finally turned something up:

http://web.camaross.com/forums/showt...+fuel+pump+gph

http://www.gnttype.org/techarea/fuelsystem/pmprate.html

guess I have to waste money on a fuel pressure gauge and test it that way, and I have no way of knowing if its the fuel pressure regulator having issues, or the pump now.

 

and page 12 finally turns up some stuff on actually debugging the entire fuel system....feel free to delete this thread.

http://web.camaross.com/forums/showt...e+clamp+pliars

http://shbox.com/1/4th_gen_tech2.htm...essure_testing

 

How did you measure the fuel pump flow? What was the operating pressure when you measured it?

 

I had no means to limit pressure except with the filter, so I ran it with and without the filter for 15 seconds into a bowl, came out to exactly 3 cups each time, which comes out to nearly 45gph with 5-10% error margin.

At this point I guess I'll burn some cash on a temporary fuel pressure sensor to hook to the shrader valve and do the ignition on and off tests and WOT.

 

Well, hopefully someone reads this far so they can answer a real question.

Hooked up a fuel pressure gauge.
Pressurized the system, 41psi, steady...never dropped off.
started the vehicle, 40psi steady at idle....
revved engine, dropped anywhere from 1-6psi depending on throttle position.

Thoughts? Bad pump? Bad regulator?

If I need to run any garage tests like the vacuum hose to the regulator off (need to find where it is) let me know....if not then tomarrow I will put the gauge on the hood where I can see it and do a WOT in gear test.

 

Testing the pump flow without backpressure is meaningless. As pressure increases, the pumps flow decreases. You have to test the flow at 43.5psi to get any meaningful data.

The typical test is to run it at idle with the vacuum line off. Any pressure in the range of 41-47psi meets spec. Then reconnect the vacuum line and the pressure should drop proportional to intake manifold vacuum. A stock cam might drop it as much as 8psi, the more radical the cam, the less drop.

But all you've done at this point is test the capability of the fuel pressure regulator and the ability of the pump to supply enough fuel to allow the engine to idle. Take it out on the road, at max load/RPM and see what the fuel pressure is. It shouldn't drop below 40psi.

 

now I'm really confused...

Hooked up the fuel line pressure gauge..... ran it at idle and unhooked the vacuum line, pressure went from 40psi to 45psi.... hooked it up and ran it on the road, kinda bounced around from 38-41psi at low rpms/loads... got it up to speed above the cam and it maintained 41psi steady.... WOT ran it twice, experienced the same power loss I've felt before, fuel pressure maintained 41-42psi.... at near-idle speeds on the deceleration it dropped as low as 36psi, but that's normal I take it. Shut the vehicle down, pressure instantly dropped to 35psi from 40, but stayed there, therefore I assume its not leaking through the injectors.

So now I'm really confused as to what the problem is. I know I have spark, just changed the opti, runs fine at high RPM's as long as throttle isn't wide open, runs fine across the RPM power-band. just at WOT from 5000+ (and steadily getting worse (more loss of power sooner, this problem started at 5500 2 months ago).
Datalogs show at this speed first the right o2 sensor drops from 900mV to 70mV, and immediately after the left now (before it was just the right), which would be indicative of fuel starvation since the feeder line comes in on the left side.
I moved all my injectors from the right to the left side and vice versa to emlinate the idea that the injectors were bad....and I believe I just eliminated the idea that it was the pressure regulator.....

So given this information I'm 90% sure I have a fuel delivery problem.....but according to all the testing I've eliminated the fuel pump, fuel filter, fuel pressure regualtor, and fuel injectors...

Any idea's?

Here's the latest datamasters....

http://www.savefile.com/files/642389

http://www.savefile.com/files/642393

and yes, the MAF code has been thrown, I just haven't reset it. It got thrown when I fired up the car after the opti install to ensure it was running before I put everything back together.