Hey Guys ...

This is for my '95 LT1 ...

I'm not 100% sure what my fuel pressure readings should be ... but after some issues that I've been having lately with what feels/sounds like spark knocking, I decided to check my fuel pressure ...

Here's what I'm seeing :::

Idle >> 35-36 psi ...
Cruising around >> 34-35 psi ...
Half to full throttle >> approx. 38 psi ... and then when clutch to shift it drops around 31-32 psi ...

Should these #'s be higher ???

I'm on the stock fuel system and have been for several years with the 383 ...

Thanks!

 

Unplug the vacuum hose from the regulator and plug the hose. You should have 43.5psi fuel pressure +/- no more than a couple psi.

 

What pressure/injector rating did you tell your tuner you were using? He would have to know that to set the injector constant.

 

I'm using 42 lb/hr injectors and this is the way the car has been set for about 5 years now ... Car was tuned then, and no issues until the last several months ... occasional spark knocking ...

Car is driven only 4 or 5 times per month ...

Replaced Opti, Plugs, wires and still see the issue of the occasional spark knocking on 93 octane from several difference gas stations ...

Just trying to run down areas and troubleshoot ...

Do you think these fuel pressure readings are ok during idle and driving conditions?

I have an appointment tomorrow to run on the dyno and see what the computer will or will not show us ...

 

At idle, with the vacuum compensation line removed: 43.5psi preferred, with 41-47psi acceptable.

Re-attach the vacuum line, and the pressure should drop proportional to intake manifold vacuum. Up to 8psi drop with a stock cam, less drop with an agressive cam.

Key test is on the road, at WOT/max load/max RPM. The pressure should never drop below 40psi.