"AlienZen" writes:

"RichToyBox" wrote in message
news:eecsc.103911$xw3.6129253@attbi_s04...
No. The pressure from the weight of the water is the same psi regardless of
the size of the pipe.

Actually, you may want to recalculate that.
A 1-1/4" pipe 4 ft long will contain0.3 gallons = 2.50 pounds
A 2" diameter pipe 4 ft long will contain 0.7 gallons = 5.84 pounds
The OP does not say how long the run is, but did say it was a 4 ft rise. Using a
2 "pipe will more than double the back pressure on the pump.

Pressure is pounds per square inch, not pounds. Try
dividing he weight by the area.

For example, the pressure at the bottom of a vertical 20
foot pipe full of water is the same regardless of pipe
diameter. It's one of those counter-intuitive things about
plumbing...