No start

[magnum10]

Decided to go out to the garage to do a little work on my car (87, 930) after sitting all winter. I have not been starting it over the winter but have had the trickle charger on it. I did an oil change and installed a oil inlet check valve from rothsports. I went to start it and it has lots of power to start but all it does is make a noise like nothing is turning inside. Its very brief about 1/2 second. I have never had this problem before.
Can anybody shed some light on this issue?
Any help with this would be appreciated.

[911SC SKI]

Do you mean the starter motor makes a noise, but the engine doesn't turn over? Sounds like the solenoid might be seized and not throwing-out, if that is the case? Give the solenoid a tap with a hammer, is the typically approved method, I believe?

PS I am not a mechanic

[magnum10]

No solenoid. EFI.

[Porsche 935]

Every engine has a starter motor, has nothing to do with weather it is efi or not.

[magnum10]

Yes. Your right. Don’t know what I as thinking there. I guess I’m showing my lack of knowledge, hence the plea for help on this.

[magnum10]

Well. Upon fear that the oil inlet check valve that I just bought did not work and I would damage my engine, I drained the oil and installed another S tube. Still had the no start issue. I went underneath and gave the starter a few encouraging taps. Did nothing. Decided to take the car off the jack stands and pushed it to the end of the garage so that it would roll down the driveway and pop the clutch. It did not start on the first try but it must have turned over the engine slightly and it fired up on the 2nd attempt no problem. Kinda odd that it would seize up just enough to prevent it from starting after sitting over the winter. I guess it would be beneficial to start it every so often over the winter. I still want to install the check valve, guess I will do it in the fall and see how it goes.