Doesn't matter what the pump puts out as long as it meets the supply the tbi needs. That's why there is a fuel pressure regulator built into the throttle body.
That's an incomplete statement. The fuel pressure regulator cannot raise low fuel pressure caused by a pump that can't keep up as demand increases. It is not an uncommon scenario to have proper fuel pressure at idle, but it drops off drastically as engine load and fuel demand goes up. We measure fuel pressure, but what we are also measuring is the pump's ability to supply volume. If a pump can't supply volume under a load, the pressure will drop as volume fails to keep up with the demand.
Yes, the regulator does bleed off excess available pressure. It's been a few years since I deadheaded a TBI pump, but IIRC it was around 20-25 psi. And that is then regulated down to 9-13 psi.
It's important to know what fuel pressure is under all conditions, and that it remains constant and within specs. Too high or too low, and the system has to start compensating. And it is almost impossible for the system to compensate for low pressure before we see hesitation and low power complaints.
The OP stated he had 20 psi. If he had 20 psi removing the fuel supply line and putting a gauge on the end of it, that's a deadhead reading without the regulator or engine load in play, and means nothing. It is a useless measurement for determining if fuel pressure and volume is adequate under all loads. And if he had the proper in line adaptor to measure fuel pressure, 20 psi would be too high, unless he had a tune that required that fuel pressure.
There is an inline adaptor that goes in place of the fuel filter with a test port on it that you hook a gauge to. Then you run a 6ft. hose to your gauge and measure fuel pressure while driving. It is the ONLY way to accurately measure fuel pressure.
Tom
