Oil Pressure Gauge problem on 89

[mrluhman]

Since buying my 89 blazer I have had problems with the oil pressure gauge. I have had a new dealer installed GM crate 5.7 put in recently and all systems are go and humming in the new power plant, which affirms to me that its the gauge and not the engine. After I start the vehicle the oil pressure goes up, then it goes down, then it just randomly fluctuates with no rhyme or reason. It mostly stays pegged at highway speeds. Before I tear into this project where should i start. Simply get a new gauge off LMC or a junkyard, or is there a sensor I should check first. If so where is it located? Has anyone else had this problem? I know this is a noob question but I seem to have the worst luck on buying and installing parts I dont need. Thanks in advance!

 

[4X4HIGH]

I had the same issue when i changed my engine out last year. It is a bad sender and it is located to the driverside of the distributor. There are two different senders either a 1 wire or a 3 wire. The 3 wire sender is dual purpose to operate the oil pressure gauge and also the fuel pump relay back-up. It is usually easier to remove the distributor to gain access to the sender.

 

[mrluhman]

thanks 4x4high

you hit the nail on the head. i would have been disappointed to get a new gauge and have the same problem. thanks again.