I've measured the output PSI at just under 4psi which is in the correct range of 2.1 - 4.3.
The fuel output, though, was 13 ounces in 30 seconds when specs call for 16 ounces. Does this difference of 3 ounces suggest the need to replace the pump?
I've changed the fuel filter. Even drained the fuel tank looking for any reason to flush it. Nothing. Clean.

 

Old fuel pump put out 13 fluid ounces of fuel per 30 seconds.
New NAPA fuel pump is rated at 21 fluid ounces per 30 seconds.
Carb problems? Check that old fuel pump first.

 

Most fuel pumps have a Gallon Per Hour (GPH) rating. All the pumps I checked on Rock Auto have a 20 GPH rating. So let's do the math. 20 GPH divided by 60 minutes equals. 0.33 gallons per minute. Since you only measured in half a minute (30 seconds), divide that by 2 (in half) and you get 0.166 gallons per minute. To get ounces, 128 ounces (how many ounces in a gallon) divided by 0.166 equals 21.248 ounces.

13 ounces in 30 seconds? Sound like a tired pump to me.

 

I'd watch where I bought it. I just had a RockAuto pump go out in less than a year. I can't remember the brand on it. I'm just grateful it's not like a modern truck so I didn't need to drop the gas tank.