PUMP QUESTION

[hotrod]

even with the whole water system disabled the car surges and is erratic on part throttle

my first guess would be to check for air leaks in your system. You may have a loose clamp or something that is causing the erratic preformance.
Your discription sounds much like what a car does at part throttle when the air fuel mix is too lean.

You might want to try a smaller jet to see if that helps, your loss of power, water injection will cost you power if you turn it on too soon or spray too much. It also will cost you power if the air fuel mix is too rich. Sounds like you have a couple issues to sort out. I'd fix the bad behavior with the WI shut off first, then take a look to see if your power is still down.

Larry