All,
This problem is driving my up the walls. I have a 1989 Firebird, 305,TBI. The mods are headers, edelbrock intake, dual roller timing chain, hypertech chip, 160 deg stat and fan switch, matched injectors. TBI spacer. I just installed an inline pressure gague and I also have a adj. fuel regulator. Finally I have an auto meter air/fuel ratio (ATM-4375) meter installed. Now at idel the pressure is anywhere between 9-12 psi. I adj the regulator (tighten the spring) restart the car and psi doesn't change. I adj the regulator to full rich, restart car, no change in psi. I remove the adj rod and now I have 11.5 psi, constant. I let motor warm up, take a look at my air/fuel ratio, and according to the meter I am still running lean. The meter never even toches the rich. I take the car for aa ride and she has power, and she seems to be running ok, except that the a/f meter is telling me she is lean. I get home, pop the hood and look at the psi and now I am at 7psi. Now I am confused, do I have a bad fuel pump, if so what kind do I need. Shouldn't I see constant psi at idle?? All ideas or comments will be appreciated.

Brad
San Diego

 

Try pinching off your return line. The pressure should spike to something like 20 or better psi. If it doesn't, you have a weak fuel pump. Sounds just like the problems I've had with my 9c1 Caprice. Swapped in a new FP and I have constant steady pressure out the wazoo.

 

I am gearing towards that problem. I believe its the fuel pump, just want to get other comments. I really dont want to drop the tank however it must be done.

What is a good pump to buy as a replacement for the stock one.

 

I've heard of people using an external fuel pump and just letting the fuel be pulled through the one in the tank. It might be something you'd like to do instead.