Whats the stock fuel pressure on a 84 pontiac firebird? what gph does the stock fuel pump flow? and last but not least is the fuel system a return system or returnless?

 

Fuel pressure should be around 6 PSI, but the tolerances on the pumps can cause it to fluctuate higher or lower than that, depending on how that particular pump was screwed together. The system uses a return line that is built into the side of the fuel factory pump (most aftermarket pumps do not have a return line, but can still be used as a direct replacement regardless- just cap the factory return line and forget it).

I would have to estimate the factory fuel pump provides about 60-70 GPH vs. an aftermarket one that would typically be in the 100+ range.

 

Well, just to add to the post, I just went through this test. The GM S/M I have gives these spec's. With the gauge connected to the fuel line (no tee) you should have between 5 1/2# to 6 1/2# of fuel pump pressure. I had 5 1/2#. There is another test called the fuel pump flow test. The fuel pump should pump one pint in 30 sec. My pump, pumped (1) qt in 30 sec. I then installed a tee in the fuel line at the carb and the gauge read 4 1/4# of fuel pressure. All of these test are done with the eng. at normal operating temp and at idle. I also have an elect. fuel pressure gauge (a must with NOx) in the car. At idle it reads between 3 and 4# and at hwy. speeds it reads around 3#. At WOT it reads between 1 1/2# and 2#. I shift the 355 at 5800 with no fuel starvation problems. When I hit the button at WOT an elect. Holly pump is turned on automaticaly buy a micro sw. mounted by the Q-Jet sec. linkage. The fuel pressure gauge in the car reads between 5 and 6# of fuel pressure.

Auggie