1988 oil pressure ONLY reads 80

Even if I turn the key just to light up the dash not to turn the car over the gauge reads 80. It has never read anything but 80. I have replaced all the oil pressure sensors. Still nothing different ? I have considered maybe Autozone sold me shit parts but I just don't want to chase a wire. Hours of work and lots of money because I pay someone to work on my car. Please help ! 

Remove tan wire from sender. with a jumper, short tan wire to engine ground. Turn on  ign, gauge should read 0 pressure. If yes = bad sender. If = still 80, remove cluster, and repeat test by jumping tan wire at rear of cluster to ground. If gauge reads 0 = open tan wire to sender. If still 80 = bad cluster.

Pretty simple circuit, actually.

Remove the cluster ? The whole dash will come out for that ! Way expensive. Shit. I will post results when I get a chance to address this problem.

dont let all the wires scare you its not too bad a lot of it is computer related the gauge wireing diagram is in the haynes or chilton book  power to the dash and grounds thru the sendor simple stuff

Stuck at 80 can be just a bad ground. I know because I've moved my tree off the block with a ss hose and I get the same reading unless I ground the tree (with the sensors) to the engine block with a ground wire. So maybe yours is just corroded enough and not grounding via the threads.