hi I got a 91 z28 5.7 tpi it is running rich when its cold it will crank once and start most of the time but when it is warm it will crank for about 30 seconds and start and then have a really bad fuel smell. I have to have the pedal to the ground so it starts easier. I have a new CTS and MAP sensor and also have a new fuel pump because the one in it right now makes a lot of noise. the car while driving will back fire after letting go of the pedal at higher rpms too. any suggestions on what the problem could be?

 

I'd guess a leaking injector(s). Access a FP gauge and see if the pressure drops real quickly after shutting it off.

 

I tested the fuel pressure with key on but engine off it would hit 40-42 psi then start dropping. but with engine running it would stay at 42 psi then when turn it off it drops pretty quick. im kinda thinking regulator. any thoughts?

 

When the fuel system goes through the 2 second prime it should hold fuel pressure for atleast 5-10 min before it slowly bleeds down. If you pull the fpr vacuum hose and have evidence of fuel the diaphragm is torn. Bye pinching off the jumper line on the return side. That is the 5/16 line coming off the fpr. at he fuel pressure will hold longer unless you have a torn diaphragm or leaking injector or its bleeding back through the pump or pulsator.

 

as soon as the fuel pump kicks off it starts dropping and only takes about 30-60 secs to hit 0

 

Had similar prob (w/o the smell tho), and it cleared up when timing was set to 17 degrees.