How much pressure change should there be on a stock regulator when disconnecting the vacuum hose? 96 B18C1.

Range for my motor in the Helms is 38-46 psi with the hose on. 47-54 psi with the hose off/pinched.

On my car the pressure under vacuum is set at 42 psi. Hose off/pinched it goes to 48 psi. Pressure is in range according to the Helms. Car runs rich though under idle/light throttle. If I use the B&M add on regulator to lower the pressure to the lower range given in the Helms the pressure is not where it should be under full throttle.


Mine is 6 psi difference from hose on to disconnected/pinched. Is this normal or is my FPR worn out and need to be replaced?

 

6 psi is an alright change. What's your pressure without the regulator? I'd be more comfortable going with a aftermarket fpr.

 

This could be a dumb question, but how can pressure be measured without the regulator? I can't think of any easy way nor reason why removing the regulator would be relevant.