92RSFivePointSlow

92 LO3. I have been running my FP at about 14psi for a while now, but today I needed to lower it for emissions and even if I have the spring platform all the way down, it only lowers the pressure about 1/2 psi. I have replaced the meter cover, the diaphram, the regulator, and the spring with the one in my stock 89 truck and the pressure still doesnt fall much below 14psi. I have a JET regulator and I KNOW I have gotten it as low as 7 psi. Whats going on here???
I don't see how a failing pump can cause too high of a pressure, and I also blew some air into the return line at the throttle body, and it doesnt seem to be clogged, although I wouldn't call it "easy" blowing through it.
It's the stock pump, and I haven't made any changes since the last time I was able to sucessfully lower the pressure.
Any suggestions?

ShiftyCapone

iTrader: (7)

Did you put the stock regulator back on? Are you sure of your PSI numbers? How are you measuring them? Do you have a gage? Are you running silly rich er what exactly is the problem. A little high FP shouldn't cause you to have emissions problems.

92RSFivePointSlow

Yes, I put a stock one on, as well as a whole top cover from a "known to be within spec" unit. I have used the JET regulator for years I know how it works, it definetly goes lower than the standard setting. But according to my in-line liquid filled Marshall gauge located in the "in" line about 2 feet before the throttle body, it's at 14 or 15 psi, depending on the temperature. This same gauge has always been accurate, and I have gotten it to read as low as 7psi with the same JET regulator, and sucessfully passed emissions. This time around, I almost passed, but then all of a sudden the pressure became "unadjustable" and all the sniffer readings skyrocketed. All I'm trying to do is set the car up the same way I had it when I passed two years ago, but the pressure isn't going back down. I'm going out to blow 50psi of air through my return line, will check back and let you know how that went.

ShiftyCapone

iTrader: (7)

The fuel pressure gage that you have installed now will only measure the pressure coming from the tank and not whats entering into the TBI unit. That number will tell you what your line pressure is. Adjusting your regulator changes the amount of fuel that enters into the injector pod and not whats in the line.

92RSFivePointSlow

I installed that gauge 3 years ago, and I installed it before I started playing with the FP, just to see if it was giving a good reading. With the stock regulator, the gauge read 11psi, and that seems accurate to me, since factory spec is 9 to 13 psi. Then I put on the adjustable regulator and was able to have adjustability from about 8 to 15 psi, by simply turning the 3/16" socket screw. Everything has been fine for the past three years with that setup, and I have had adjustability.

My problem now is that I don't have adjustability. I can't lower my pressure.

My question is: Why can't I lower my pressure any more?

I blew compressed air through the return line and I can hear it coming out the filler neck, so the return line isn't clogged. Is this a problem that no one has had before? I'm really stumped.