Oil pressure gauge spiked!!

[psuchemboy]

Well I got my "newer" motor in my truck now.

I put a new temp sensor in because my old one never moved unless it was almost overheating. WOW... It now works after all these years.

I put a new oil sender/switch on that Autozone told me would fit. I get everything together and the oil gauge is spiked when running and at 90 when off. It is also at 90 when unplugged. Damn... I put the old sender/switch back on. Now it reads about 60 at all times. Before I fussed with the whole project the oil gauge worked just fine. Is there a way to reset it?

Any suggestions?

Here's a description: 1993 block with flat top pistons. Newer rings and crank. GM performance vortec heads with thinner head gaskets, roller cam from newer TA, Edelbrock RPM intake, Summit headers, and holley double pumper w/holley blue pump and regulator. All emissions removed except PCV valve. This set-up has about 5k miles on it. I bought it from a guy while it was still in his truck.