[Captkaos]

On TBI models the pump could be a 30psi in the tank, (I am thinking it was more like 20-25) but the TBI had a regulator on it to keep the pressure between 13-17. If you put an external regulator on it, it should work fine.

I am still a little confused here, but the pump in the tank should go to a switch that selects the tanks. From there a supply line got to where the TBI was mounted (at the back of the firewall) from the TBI, a return line should go back to the tank/s. It shouldn't go back to the switching valve. The whole system would have the full pressure on the components up to the inlet on the TBI. The outlet side you would see the pressure drop. I would think the Switch went bad because of the age, or the lack of use over time.

The one we installed was a '78 pickup with a mechanical pump that we swapped motors from a '90 model which doesn't have the mechanical mount drilled/opened. We installed a electric pump that flowed about 25psi and ran a regulator on it to get it down to 7psi.

Originally Posted by landpro00

Swapped from a TBI to a Edelbrock carb.

Just looked at my Chiltons manual and it says ALL V8's starting in '87 have fuel pressure ranging from 35-47 depending on engine. For a '87 454 it says 34-46PSI.

On yours, was it originally TBI? What year?

THANKS!!!