Fuel pressure ?
 

Just bringing our 331 to life, got the fuel pressure set for 38 at idle, when motor starts to rev higher, fuel pressure drops off to about 25. We've got 24 lb injectors, and a 190 in tank fuel pump.

Do we have a vacuam leak or do we have too much motor for the stock fuel system and 190 fuel pump? We will be upgrading both the fuel system and fuel pump - when we install the supercharger this winter.

Re: Fuel pressure ?
 

If the vacuum drops off, the pressure will go up....what's the vacuum??

Re: Fuel pressure ?
 

24#'ers won't satisfy a healthy 331 for very long. I've tuned two nice 331 combos recently and one was pegging 30# at 5500 rpm and the other was at 90% duty cycle at 6000rpm. They're making 380rwhp and 360rwhp, respectively. On a return-style system, if your fuel pressure begins to fall off with RPM, then the fuel system isn't up to the task.

Re: Fuel pressure ?
 

We'll check the vacuum this weekend. Fuel pressure is not going up it's going down.

Our plans are to upgrade over the winter to 60#lb, new fuel system Aeromotive, or others if anyone can suggest, with our Vortec T-trim sitting in a box ready for its new home.

Would upgrading the fuel system now without upgrading to 60#lb injectors or MAF help the problem of dropping fuel pressure? We're doing our car in stages with the ole $$ money factor.

We've got a stock fuel tank, is that return-style or not? If it's not, should we also upgrade to a return-style tank?