I want to start by mentioning im not a mechanic and outside of air, fuel, spark, timing and compression I'm pretty lost. I have a 88 firebird formula one that has a Chevy 350 ( I think from a iroc) with a 700R4. Has a new fuel pump and holley 650 carb also has a new Jegs fuel pressure gage and a relatively new fuel pressure regulator that came with the vehicle and this setup has a return line. When I start the vehicle it has about 7.5 lbs of fuel pressure that will quickly start to drop as the car idles. If I drive the car even for 5 minutes the fuel pressure will drop to 0 the car still runs. I'm scared to really take it any farther than that. I'm at a loss for what's causing this problem I've moved the fuel pressure gage from up by the carb to actually on the regulator and problem still persists. Can this be caused by the fact that it has a return line? It's a electric fuel pump.

 

Do you have the model number of the regulator? That will help determine if it is a bypass regulator designed for return style fuel systems or a dead head regulator designed for no return systems. If the wrong type is used it can lead to issues like this.

 

I don't have it currently but I will make a effort to find out. It does have a place for a return (meaning its labled "Input" " output" and "return"

 

When the fuel pressure drops to zero does the car eventually stop running? Have another gauge to test with? That cheap liquid filled gauges are known to be junk.

 

Yes so even at 0 psi it still runs. I don't notice any noticeable difference in the performance. Its never really run great. I did move the gauge and the problem still persists but I've never been able to get it to shut off

 

Sounds like a gauge problem, if the keeps running and running fine.