I just recently purchased my first Ford Ranger, don't stone me but I am more of a Dakota guy. I couldn't beat the deal on this one though and I bought it from the original owner. It's a 1994 extended cab 4x4 with a 4.0L, automatic.
Whats happening is I am getting erratic oil pressure readings from the gauge on the dash. Most days the gauge goes up to in between the M and the A in Normal and stays there, whether I'm driving 70 down the interstate or sitting idling at a stop light. Other days it starts off there and within 15-20 minutes it drops to between the O and the R and that is where it stays. Other times when you start it it goes no further then between the N and the O and stay there for about 10-15 minutes then pops up to the usual position. The reverse is also true some days it starts off there it should and drops way down. I have changed the oil in the truck since purchasing it. I have also looked over the oil sending unit for a loose connection or weeping oil, all appears well there. The cold seems to effect it some but I haven't been able to catch it every time to say for sure. Could it be the gauge in the dash itself causing problems? The sending unit on the engine is only $9.00 bucks but I don't want to mess with it if I don't have to because like I stated before its cold out and I hate working out in it! Thanks for your time!

 

If it's too cold to work on take it to a decent mechanic and have them put a mechanical gauge on it and get a real reading. It could be the sending unit that's giving you the odd readings. Also, at one time back in the dark ages, Ford had a 'constant voltage regulator' in the dash could also cause 'wandering' readings on an oil pressure gauge.

Do the simple things first before tearing into things like the oil pump.

 

I will just wait until the weather breaks to work on it. I don't take my vehicles in to get them worked on. I was a mechanic for 20 years so no need. I just was wondering if my issue was some thing common to Rangers and caused by something other then the obvious.

 

As long as the lifters are not making a noise you have enough pressure.