Should the fuel press. be set with vacuum on or off and what press. is typ. for an L98? This question is for my friends 89 vette.

 

Disconnect the vacuum line to set fuel pressure.

 

stock is 43 psi vacuum line off. most have seen improvements at 52 psi.

 

Thanks for the replies. I'll pass the info on to my friend. I think he was up to around 53 psi, but I don't know if that with w/ vaccuum on or off. Thanks

 

Vacuum line ON will lower the pressure u see, when u floor the gas pedal, u lose vacuum, n the pressure raises up to the PSI that you set the regulator to with the line OFF (setting it with line OFF is basically the WOT/Maximum pressure your car will have). If his is 53psi with the vacuum line on, then he's got around 60psi with the line off and that, in my opinion, is way way way too much - so chances are its 53 with line off