i have a 454 in a 78 camaro,everything is new.when the engine is running at idle and i snap it wfo it backfire,spits and sputters then revs up.if i take it up to about 1500-2000rpm and snap it wfo ,no hesatation ,none,sounds like a pro stock.my question is,do you think i need to switch out the accelerator pump,im thinking it isnt getting enough fuel when i go wfo.this carb. is a brand new holley 750 double pumper.it has 72 or76 in the primary,i cant remember,the power valve i changed to 3.5 because my vaccum in drive was about 5.5-6.0.if i change the pump ,do i need to change the squirters.anything you guys can tell me that can help me will out will be very appreciated.oh and one more thing,if i have the car running today and i go back out the next day and try to start it ,its like it has no fuel,no fuel in the glass filter and it has a hi-performance 396 fuel pump on it.its like all the fuel drained back to the tank.thanks let me know something

 

Check the pump and make sure it is adjusted correctly. The little arm on the bottom should have almost no free play (.10 inch play is fine). Also check all the basics, float level, fuel pressure etc. Changing the pump will only give a longer duration fuel shot, you may need that but I bet it is more of a squirter/pump adjustment than anything else. BTW the timing is set correctly right?