Guys I have an old 88 F150 with a 4.9. I have noticed the oil pressure gauge reading lower over time.

I had this problem many years ago with this truck and replaced the sending unit and this item in the harness I'm calling a resistor. It just plugs onto the sending unit and then into the harness. It does have what lookd like a resistor symbol on it.

Anyway if you take it out and plug the harness direct to the sending unit the oil pressure gauge jumps up from the N of Normal to the M where it used to run. I'm thinking the resistor has issues but I don't know what purpose it really serves. Any knowledge on this one? Just thinking aobut leaving it out. I did notice that when you start the truck the gauge now jumps up to M very quickly when you get oil pressure. With the resistor it goes up at 1/3 this speed.

 

don't waste your time or money on the stock oil pressure guage. it's a 7psi pressure switch that is either on or off... there is no variable oil pressure being shown!

You need to do a conversion to a variable oil pressure guage which cost about $20 and gives you real time oil pressure instead of a "yes you have oil pressure" or "no you don't"...

 

Has anyone tried to convert the existing dash gauge from a glorified idiot light to something that really shows pressure ... by replacing the oil sender with a real sensor? If I could put the diagrams in, I would, but I can't figure out how, so I put the diagrams on my blog:

Tim Gatton's Basic Blog

thanks

tpg