I was told to set it at 38# static (no vacuum line hooked up) I am experiencing a lack of power in 3 gear and on and also a bucking (Car surges back and forth) problem in low RPM when I snap open the throttle after cruising at a constant speed.

Can these symptoms be caused by too low a Fuel pressure? I know top end power would hurt but would it cause a hesitation and bucking when lets say I am cruising in 3rd at 40mph and punch it. I have heard it should be set at 43.5# with out the vacuum lines but does this also apply for modifiied LT1's?
396 Stroker 9:1 Comp, ATI supercharger 7 psi of boost, MSD 50 lbs/hr injectors
Thanks

 

I raised the FP up to 42 and same damn problem Only it seems worse now.

 

my friends camaro is experiencing the same problem ... what gives .. i think this may be vacuum related.... anyone ???????

 

Its the after market regulator. Does not matter what you set the reg at the ECM will change it (with or with out programing). I had this problems with my AM FPR, and with holly. Put the stocker on and bam the car has better pressure, and runs a lot better. Try the stock unit it will take 600hp no problem.

 

A few clarifications......

The ECM will not change the fuel pressure, only the part throttle fuel curve. It can only do this within a limited amount of correction. Yes, the computer will correct a lean mixture due low pressure & therefore also add fuel at full throttle, but it will not lean the mixture at full throttle if it is rich at part throttle...... full throttle is only correcive in the positive direction.

You need to verify your long term BLM's to see what the car wants fuel wise at part throttle. Once you get your injector opening & injector size constants correct for part throttle then worry about full throttle.

50# MSD injectors seem to be the worst possible injector to tune on these cars. You have to see the block learns at idle & part throttle & adjust your tuning from there. I recommend setting pressure near the stock setting give or take a few#. 42-46 is a good starting point. Remember that many aftermarket FP regs. will increase pressure with boost. The 50# MSD locks up like the stock injectors around 70#, so be careful.

 

Does the fuel pressure drop when you punch it? Or does it drop at all. What is the rest of your fuel system components comprised of?