Mitsubishi Repair: 90 eclipse 1.8 oil pressure, oil pressure gauge, oil pressure sending unit

Question
I just replaced the timing and balance shaft belts starts up fine runs good but has no oil pressure. I just read one of you replies and am getting ready to check compression. I was going to check the oil pressure sending unit but on the oil filter holder there are two sending units one big on that looks like a can and a regular looking sending unit  what are they and which is which thanks Jeff

Answer
Jeff,
The bigger unit you see on the oil filter bracket is the oil pressure sending gauge unit.  This is what sends the signal for the oil pressure gauge on your dash to move.  The smaller sending unit is actually the oil pressure sensor switch.  This controls the oil light that will come on if your car's oil level is low and getting little or no pressure.  If your oil light is not coming on, you may just have a bad gauge unit, or the wire that connects to is not getting continuity.  The gauge is easy enough to check if you can remove it.  It's pretty inexpensive if it needs to be replaced.
Good luck!