Does anyone have some experience using the vacuum-delay valve with the VRFPR? is it a must have? http://www.top-downsolutions.com/pro...products_id=97

That is a good find Thomas ! I would have thought just the opposite that is the opening of the T blade is so quick(MAP >) and the AE lags the on rush of air and mani vac drops pulling fuel out of suspension. As a side note I increased the TF fuel and that helped me(7.4L TB). Now a better fix may be sequential opening of the blades. They state the FP increases with loss of vac or increased MAP and let off gas the opposite occurs. I would expect the issue could be present when using lower fuel pressure(ie 10-13) and stock injectors. Grumpy once said higher pressures make the TBI more efficient. And that is what GM did in trucks(30 lbs FP) 1995-1996 along with 42 lbs injs.

The vacuum delay valve is a bandaid for VRFPRs when the ECM can't compenstate for the change in fuel pressure. It helps to smooth the transitions.

A better system is a VRFPR tied directly to the intake manifold and an ECM that adjusts to the change in fuel pressure.

RBob.