got a 1998 sunfire ,waterpump went out replaced it . now it wont start got a new starter and now it will start with a jump but wont turn off and the key switch will not turn off, have to un plug the b

Not sure where the water pump is on your motor and the connection between the two is a little hazy, unless it's located somewhere above or near the starter solenoid....when you replaced the starter, did it come with a new solenoid mated to it or did you have to transfer that part over/or it's remotely located?

Yes it has the switch on it...they told me when i bought it that mine was good but of course i argued it was...lol i went through this twice and the same thing .will jump start but the starter gets stuck and the key switch will not cut the car off......have had three starters put on and I am begenning to believe that the starter has nothing to do with my problem could it be some computer or theft protection or something,?????so confused !!!@!!!!

See if you can find the starter relay. According to some info I found online, pertaining to a 96 Sunfire, originally they had no starter relay but the wiring through the steering column was catching fire, so they fitted a modified wiring harness and a relay into the setup and the relay was mounted near the middle of the radiator they say. Wondering if yours got soaked with coolant and is supplying power when it shouldn't be. If you're able to locate the relay, forget trying to test it with a meter, you're just wasting your time with the price of relays these days. ;) Purchase one and if it doesn't fix your problem, return it. What I do if I'm in a pinch is find another, identical relay in the car that runs a system that isn't essential to start the car (like ABS for example), and swap it into the Starter relay position and try it. You're going to have to match up the spade location and if the relays are original, they're going to be sourced from the same place, so if they're matching they will have matching numbers and stamps as well.