Well - got the car running today. I had pressure at the rail but the injectors weren't spitting anything out. I got an extra four from Albert and then I went through them all. I took off the cap and gaskets on the bottom and then using compressed air I blew carb cleaner through the injectors. I had a low voltage hook-up (about 3 volts) that I hooked up to the injectors to actuate the valve.

After getting the car started though I have a follow-up issue. The guage cluster is showing little to no oil pressure. I pulled off the sender and replaced it twice with two decent looking used ones and no change. I swapped out the cluster for another one and no change. I put a mechanical oil guage on and when I started the car it showed 95 psi at idle.

After that I turned the ignition on my 951 on and tested the slide on connector on the oil pressure sender and got about 1.16 Volts. When I tested the one on the parts car I only got about 0.19 volts. What I am wondering if where the sender pulls power from - DME or that part of the harness that goes over to the fuse box? As I recall there is a power wire and then a signal wire coming from the back of the sender. I am also wonder if there could be a short or a partial break in the oil pressure sender wires that go behind the timing belt cover around the thermostat housing? Unlikely I suppose...

 

Could only be 1 of 4 things...

1)Bad Sensor
2)Bad cluster
3)bad wiring
4)Bad Ground point 3 in drivers footwell to firwall

Both sensor wires go to the cluster, the cluster then connects to the MPIII ground point..

Either the power in the cluster is bad, the sensor is bad, you gots bad wiring or a bad/dirty ground... I would go for the grounding point first... as it is probably the easiest to fix...

 

could you just ground the sensor wire and see if the guage moves this would rule out bad sensor?

 

Possibly. Checking the grounds is a good idea too.


I am reading the wiring diagrams or attempting too. Trying to figure out where the wires go that connect to the sender...

 

Did you check the ground behind the firewall in the battery tray area? I have had that just slightly lose once and it caused all sorts of false gauge readings.

 

I am going to try that. From reading the wiring diagrams it looks like one of the wires from the back of the guage grounds out at one of the spots under the dash to the left of the cluster.

Wish someone knew for sure where those wires go. When I get home I have a spare engine wiring harness and I am going to see with the multi-meter if I can trace them.

 

Josh - give me a shout later and I'll stop by.

 

Looks like the WK marked connection on the back of the sender goes to pin 6 on the connector in front of the fuse box. The other connection marked G goes to pin 9.

I guess next I can check that i have a good connection between those two points to rule out trouble with the engine wiring harness. Wonder where the trail goes from those pins? I think one goes to a ground - hoping to check that tonight.

I looked at the ground under the dash last night and they were fine - no corrosion and tight.

 

From the connector they go to the gauge cluster...

 

Do you know if they go through any fuses or relays first?

 

Not according to the diagrams, sensor wires go through DME connector to gauge cluster...

The wires shown on sheet 9 terminate at block referencing F14, F15 and F16 which are on sheet 4, they are picked up in F14, 15, and 16 and run to pins 9, 10, and 15 of the gauge cluster...The other side of the oil pressure gauge runs through pin 8 of the cluster to a block referencing H32, H32 is the connectors shown on sheet 6 connected to MPIII (grounding point in drivers footwell behind dash...)

To summarize..
ONE side of the gauge and the sensor are both getting power from Pin 15 of the cluster...

the other side of the gauge is getting the signal directly from the sensor...

So your problem is either the POWER from the cluster, the ground in the drivers foot well, the sensor, or the wiring... it is a simple system that I think you may be thinking a little too much about...

REMOVE THE CLUSTER, read between pins 15 and 9, should be close to 0 ohms (power wires)

Read between pin 8 and the vehicle chassis, should be near 0 ohms (ground)

NEXT read resistance of 15 to 10, you should see a value similar to the pressure switch itself... (wiring to sensor power side)

NEXT read between 9 and 10, value should be same as previous step.. (wiring to ground side on sensor)

if any of these are false, you have a bad wire between your cluster and what that wire is running to, if the sensor is known good, your cluster is bad, if the cluster is known good the sensor is bad, if the wiring is good, and both the sensor and the cluster are suspect I would replace the sensor with a new one, as it is cheaper to replace than the cluster...

Let me know if you need more clarity...