For your multiple connection, 01dak3.9 provided the answer - use a T, that connection is most likely either a 1/4 or 3/8" NPT. You'll need a short nipple, then the T, then you can add the sensor and the mechanical pressure line. I don't think you'll need to put much on the threads, but the teflon tape is probably a good idea just to keep it all easy to disassemble later.

If you've changed the sensor and still get the same problem, you could have the following:

• Faulty new sensor - this seems unlikely if you have exactly the same symptoms as before, usually these sensors fail completely or they give a constant false output, not on-again, off-again.
• A connector or wire problem from the sensor to the ECU. This may be harder to examine, but with a wiring diagram that gives you the whole layout and the color coding and pinouts you should be able to find the ECU end, then if you have mechanical gauges, you'll need to examine the wire from the ECU to the gauge. You can do all this with a multi-meter. Without power on, you can do continuity testing to determine whether the wire has a possible break. With power on, you can see what voltage the sender is putting out when you read zero and when you read good pressure, you can then go downstream and check for that same voltage at the ECU and at the gauge.

Your mechanical gauge is a good idea to give you a quick indicator as to whether you should be playing with this or not - no oil pressure even for short periods of time can do serious damage. If you have constant good pressure, you know that you can fiddle with the electrical, but if you have a flaky mechanical pressure indication, I'd be inclined to consider the pump assembly as the culprit. With a good pump, there should be no gaps in the oil pressure - the pump is always in oil so even priming isn't required.


If it's mechanical, there's one other consideration - the linkage that drives the oil pump. You'd need to have a look at a service manual to see what that would be, I've often seen the distributor shaft used to drive the oil pumps and when distributors were no longer used, that mechanism was still used to house the cam position sensor & that shaft extended to the oil pump, just like the distributor shaft did in the past.

 

Well, I replaced the sensor again. Woke up this morning in the -1 degrees F temps and the truck showed oil pressure right away like it should. Since the problem isn't consistent, I will need to check this over a period of time to verify that it is fixed. I didn't test with the gauges because I saw your replies after.

In any event, the oil pressure fitting discussion is something I have always meant to figure out. After having replaced the pressure sensor, I can tell you that there isn't a lot of clearance between the sensor and the serpentine belt. But I would imagine that the tee for a small pipe fitting like that might work. I will check the two just to see if it is possible.

As for the linkage, the oil pumps on the 4.7 are driven off of the crankshaft itself, so no worries there. It does make it a brutal replacement though for the oil pump, should you ever need to replace it. Right now the pump has about 100K on it, I put it in new when I swapped engines.

It could still be a wiring issue, and I did try to test continuity, but was not able to. I think the probes on my multimeter were too large to fit into the pin openings on the PCM connector. Do you guys use special or thinner probes to test these connectors? I have two sets, both standard size, one is a Fluke tester and one is Craftsman.

 

If you're short on room for adding a mechanical gauge (should you need one now), you can try using some short nipples and elbows to point the connection into an area with more room.

For quick probes of any size, use some alligator clips and straight pins - pick the size of pin you need and clip onto it with the alligator clip. I use small straight pins to stick through the insulation, directly into the wire, and when I'm done, I put a small dob of ATV or liquid electrical tape onto the hole to keep the moisture out. I also use alligator clips specially designed to go through insulation, they have thin needles in the jaws. These make life a lot easier in trouble shooting, you just need to remember to plug up the holes once you're done.

 

oh, i forgot that the *.7's have the port elsewhere. the pushrod motors have the sensor underneath the distributor.

What we did on the camaro, we ran a hose off the back of the block to a spitter for the oil pressure gauge, oil pressure kill switch, and the computer sensor. That way there was 1 connection on the motor where it was hard to reach and 4 on the firewall where we could easily get to them.