Could a fuel injection pump be use to operate water injection,was going to make a system myself using pressure/air temp switches.

 

NO, will rust inside after a short while.
tabetha

 

that answers that then
cheers

 

surely u could find some sort of 12v water pump fit for purpose not sure what tho

 

There are loads of water pumps, more than capable of the pressure needed for water injection about, ie a bog standard screen washer pump from some cars, or headlight washer pump, std mondeo one about £8 from Halfords!!
In the traditional fuel pump fitted on cossie etc, the whole inside of the pump complete with electrical connector points has petrol flowing through it, but with water brings oxygen/moisture and so corrosion occurs.
tabetha