I swapped a 355 sbc into my 89 2.8 multi port fuel injected firebird. it will start and run for a few seconds if i pour a little gas straight in the carb, but if i don't i get nothing. The two hoses that come up in front of the master cylinder, the larger one i ran across the motor to the carb with a straight threw specter fuel pressure regulator [adjusts from 1psi to 5.5psi]. the other smaller hose i plugged off. i primmed the crap out of it and poured a little fuel down the top of the carb started it and it ran for about 2 minutes then died. after anothr shot at it the same thing happened. there seems to be alot of pressure behind the fuel pres regulator, i primmed the crap out of it again poured in a little more gas in the carb and started it up. i was trying to watch the spray of fuel in the ventures, at first great but as she ran it slowly stopped, THEN she BACKFIRED AND NEARLY BLEW MY HEAD OFF [117 octane YIKES] . itried to take the pressure reg off and run it direct, but it over loades the carb and dumps into the ventures. no good. i don't know exactly what i should do or what my options are so if anyone can help it would be greatly apprecciated. when she does run she sounds great.. i don't know if this helps but i'm running a edelbrock 650 carb.. once again please help

 

You'll probably want to use the return port on the regulator so you don't dead-head the fuel pump. It needs to flow fuel so it can remain cool. You may also have already lost pressure due to a damaged pump.

 

If fuel is coming out of the ventures then your float on your carb isent set right.