This is more of a just to make sure thread.

Ive read several different numbers on what your fuel pressure is supposed to be and different times. I will tell you guys what im getting to see if it is normal or not

I have the stock TPI fuel pump, a hot cam, #30 injectors, just swaped out my fuel filter, and the vacum line on the stock lt1 fpr is dry..and i dont know what else would be relevant


The pump primed engine not running: 42 psi
Idle: the needle Bounces, or shakes really fast between 34 and 42 psi
A high rpm rev: goes to about 40 psi and runs steady at about 38 psi or so.

 

At idle, take the vacuum compensation line off the fuel pressure regulator. Plug the line so you don't have a vacuum leak. Fuel pressure should be 43.5psi. GM accepts anything in the range of 41-47psi.

Still at idle, reconnect the vacuum compensation line. Fuel pressure should drop proportional to intake manifold vacuum. With a stock cam, its going to drop as much as 8psi, with a more agressive cam its going to drop less.

Tape the gauge to the windshield, take it out on the road. At max RPM/max engine load, pressure should hold at least 40psi.

The bouncing pressure at idle is probably due to intake manifold vacuum problems. Incorrectly adjusted valves and misfires can cause this condition, although that much bounce indicates a major problem. Put a vacuum gauge on it, and see if the vacuum is erratice, and if the fuel perssure is moving in synch with maniffold vacuum.

If the vacuum isn't jumping around a lot, its a problem with the fuel system - possibly the pump, or the pressure regulator.

 

wow thanks for the reply. Very informative. I did the wot test and it stayed between 40 and 42 psi. I did the test at idle again and it stayed alot more consistent. Maybe I didn't bleed the line right or something.