Basics,
What type of fuel pump? - electric, don't know the manufacture or model number.
Where is it mounted? - on the inside frame rail under the rear passenger seat area
Have you checked voltage at the fuel pump? - No, but I know it works because it's pretty loud and when it was producting 6% psi, it sounded the same as it does now.
Have you taken any readings right off the fuel pump, both pressure and flow? - No, hard to do since the car is fairly low and I just sold the car lift. Will probably have the speed shop do that.
Do you know for sure the gauge is accurate? - Don't know for sure but it's been faily accurate up until lately.
My .02 is that if you truly had 1.5 psi or 6 psi sitting at a light idling, either one wouldn't matter, you are using hardly any flow of gasoline and the bowl should be pretty much full not causing a idling issue. Especially if it runs down the road just fine when you are using a much greater volume/flow of gas.
It might be something other than fuel pump like the carb. is flooding out when idling.
