My outlet pressure is at least 10 PSI over maximum specified. AFAIK when fuel pumps go bad, pressure goes down, not up. So aside from having an aftermarket high performance pump that I'm not aware of, is there anything that could cause the fuel pump to build too much pressure?

I'm measuring several PSI over norm at the rail as well, so I suspect my FPR can't cope with extra outlet pressure.

 

the pump doesn't decide the fuel presssure, the regulator(or return line) does. sounds like maybe your return line is clogged.. to find out :
Put a Brand new line on the pressure regulator and dump it into a gas can, let the pump run through the rail and into the can instead of back thru the stock return to the tank. if your pressure remains the same as before, replace the pressure regulator.

if the pressure is the same after that, check with a diffrent guage. i have a brand new harbor frieght fuel pressure guage and it's consitantly 10PSI below.

 

I'm talking about the maximum pressure of the fuel pump. I disconnected the main fuel line and connected the pressure gauge into the end of the hose. This way there's not FPR or return line to relieve the pressure - all I'm reading is the max of what the fuel pump can put out.

I'd like to believe that my gauge is more or less accurate. As much as I love Harbor Freight, I didn't get it there.

If it's reading 10 PSI over norm, that means my actual idle fuel pressure is 10 PSI below what I'm reading, which would make it too low and I'd be running super lean, and I don't think I am. Or if similar to your case it's showing 10 PSI under, then my fuel pressure is even higher than too high.

 

could be an upgraded pump then.

 

So things like crud or gunk build up inside the pump wouldn't increase the pressure, right? And extra pressure in fuel tank couldn't contribute either? Basically what I'm describing is pretty much impossible without an upgrade, yeah?

I'm looking at the pump, and I can't find any markings or numbers on it to figure out if it's stock or not.