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Oil pressure fluctuates

My oil pressure gauge jumps all over the place when I get over 3000 rpms. At lower rpms it is in the normal range and the engine sounds ok. How can I tell if this is the oil pump or the sending unit or the gauge? This is a 1980 CJ5 with a 151ci 4 cylinder.

You can connnect an external oil pressure gauge and check the actual pressure or you can replace the sending unit and see what happens. Sending units are cheap so generally it’s easier to do this rather than connect a gauge.

If it still does this after a sending unit replacement then a faulty gauge could be considered. Other possibilities could be a shaky electrical system (alt. output) or wire connection in that circuit or the possibility of sludge in the oil pan.
I’m not leaning towards the sludge angle at this point; only covering some bases.

Thanks. I will try the sending unit. I hadn’t considered the electrical system. That is a real possibility given the vehicle’s age.