I have a 94 dodge Dakota. I got it with a bent rod and bad oil pump so I replaced the rod and oil pump and ever since the pressure gauge hasn't moved from showing completely nothing and the oil light is on, I just went through it and took the oil pump back out and re primed it by dumping new oil in it and put a new sending unit in, still nothing. Trying to fix it so I can sell it. Any ideas on what the **** it could be.

 

I got this from chapter 8E in the 95 FSM
OIL PRESSURE GAUGE
The oil pressure gauge gives an indication of engine
oil pressure. The combination oil pressure sending
unit contains a flexible diaphragm. The
diaphragm moves in response to changes in engine
oil pressure. As the diaphragm moves, resistance increases
or decreases. High resistance on the gauge
side of the sending unit causes low oil pressure readings.
Low resistance causes high oil pressure readings.
Sending unit resistance values are shown in a
chart in Specifications.

Oil Pressure Gauge Calibration

Pointer Position Resistance

Low Graduation 100ohms
High Graduation 12ohms

Diagnosis - OIL PRESSURE GAUGE
The diagnosis found here addresses an inoperative
gauge condition. If the problem being diagnosed is related
to gauge accuracy, be certain to confirm that
problem is with gauge and not with engine oiling system
performance. Actual engine oil pressure should
be checked with a test gauge and compared to gauge
readings before you proceed with gauge diagnosis.
Refer to Group 9 - Engines for more information.
(1) Turn ignition switch to ON. Disconnect oil pressure
sending unit connector (Figs. 4 or 5). The gauge
needle should move to low end of gauge scale. If OK,
go to next step. If not OK, go to step 3.
(2) Install a jumper wire from cavity 1 of sending
unit connector (Fig. 6) to ground. The gauge needle
should move to high end of gauge scale. If OK, replace
sending unit. If not OK, remove jumper wire
and go to next step.
(3) Turn ignition switch to OFF. Disconnect battery
negative cable. Remove instrument cluster bezel and
cluster assembly. Disconnect instrument cluster connector
1 (gray connector on right side of cluster).
(4) Probe cavity K of cluster connector 1 and check
for continuity to a good ground. There should be no
continuity. If OK, go to next step. If not OK, repair
short circuit as required.
(5) Still probing cavity K of cluster connector 1,
check for continuity to cavity 1 of sending unit wire
connector (Fig. 6). There should be continuity. If OK,
replace gauge. If not OK, repair open circuit as required.