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I have an 1992 RS convertible and the oil pressure is all over the place when I drive . I have located 1 of the sensor/switch ( above the oil filter ) but where is the other one for the gauge sensor ?
It's going to be lower at idle and higher the higher the rpm, it will fluctuate as you speed up and slow down, it won't stay at a steady pressure constantly while the motor runs. Coming from ford where the needle just stays in place it took a while for me to get used to as well. As long as it never drops in the red you should be fine. What's the pressure read at idle? And what's the pressure read at about 2500 rpm cruising?
It's the same sensor for both by the way. But I'm suspected your not used to how the gauge acts in these cars.
This is my 4th Camaro I have owned ( 87 SC , 91 RS and a 91 Z28 ) and all of them the needle was steady . At cruising speed it sits at a tad under 60 and at idle warm/hot it sits about an 1/8 of an inch above the red line .
I have an 1992 RS convertible and the oil pressure is all over the place when I drive . I have located 1 of the sensor/switch ( above the oil filter ) but where is the other one for the gauge sensor ?
If it's anything like the pickup trucks, there's a gigantic sensor above the oil filter for the guages, and a small switch next to the distributor for the fuel pump.
The big sensor is a common failure item on the pickups. The sensor fills with oil, and becomes very non-responsive. It may read high pressure, it may read low pressure, and it may just be plain ol' goofy. When you spin it off, the thing is heavy and some of them will "slosh" if you tip it side-to-side.
I've put three of 'em on my pickup--the one from the original engine which died about two weeks after I swapped engines, the first replacement, and the second replacement after the engine had about 90,000 miles on it. There is NO SUCH THING as a "quality" sensor, they're all imported from Asia. Taiwan is probably better than China, but none of them are "excellent".
I had fun finding a replacement sensor that would actually fit. Some of them use a larger housing, and the larger size interferes with the engine block. In another application, it might fit fine. The NAPA sensor above is the big style. I don't remember what I used that actually fit...I think it came from CarQuest.
The only sensor we have is the one next to the oil filter, it's the computer sensor, gauge sensor, and tied into the fuel system so it only runs the pump to prime at start up and when there's more than 15 psi, (on fuel injected cars). The one sensor does everything for us.
Goto parts store and order oil pressure sender for your car. I like AC Delco, but Standard is ok in a pinch. I came up with delco #10222130 for your car, but no promises.
It also might not be a bad idea to check wires. With key in run position with engine not running unplug the connector to oil pressure sender. gauage should go all the way to full. if you can determine what pin is for the gauge you can ground it to the frame and gauge will goto 0. Been a while since I've done this so i may be backwards, but always good idea to test this before condemning the sending unit.
The only sensor we have is the one next to the oil filter...
...The one sensor does everything for us.
That's different from the pickup trucks, at least my old '88 K1500.
Originally Posted by Wife'sCar
it's the computer sensor, gauge sensor, and tied into the fuel system so it only runs the pump to prime at start up and when there's more than 15 psi, (on fuel injected cars).
Not exactly. The fuel pump relay runs the fuel pump during the two-second prime when the key is turned "on". The fuel pump relay also runs the fuel pump once it gets a signal from the distributor that the engine is cranking or running. The only time the oil pressure sensor is responsible for running the fuel pump is if the fuel pump relay--or the computer and wiring harness--fails. If the relay, ECM, or the wire harness circuit fails, the "secondary" system of the oil pressure switch and it's wire harness will power the fuel pump when the engine has oil pressure. When the fuel pump relay fails, the pump won't prime, and the engine will have to crank long enough to build oil pressure, so it leads to an extended cranking time before the engine fires.
That's different from the pickup trucks, at least my old '88 K1500.
Not exactly. The fuel pump relay runs the fuel pump during the two-second prime when the key is turned "on". The fuel pump relay also runs the fuel pump once it gets a signal from the distributor that the engine is cranking or running. The only time the oil pressure sensor is responsible for running the fuel pump is if the fuel pump relay--or the computer and wiring harness--fails. If the relay, ECM, or the wire harness circuit fails, the "secondary" system of the oil pressure switch and it's wire harness will power the fuel pump when the engine has oil pressure. When the fuel pump relay fails, the pump won't prime, and the engine will have to crank long enough to build oil pressure, so it leads to an extended cranking time before the engine fires.
I didn't say it runs the pump, I said it's tied into the system. It's looking for at least 15 psi. If your car will prime the pump, then start for a sec then die, that's a sign of a bad pressure switch. The computer primes the system, car starts, then looks for the psi from the sensor, if it's to low it cuts fuel again.
Goto parts store and order oil pressure sender for your car. I like AC Delco, but Standard is ok in a pinch. I came up with delco #10222130 for your car, but no promises.
It also might not be a bad idea to check wires. With key in run position with engine not running unplug the connector to oil pressure sender. gauage should go all the way to full. if you can determine what pin is for the gauge you can ground it to the frame and gauge will goto 0. Been a while since I've done this so i may be backwards, but always good idea to test this before condemning the sending unit.
The OPs gauge is working correctly, there's nothing for him to fix or replace.
I didn't say it runs the pump, I said it's tied into the system. It's looking for at least 15 psi. If your car will prime the pump, then start for a sec then die, that's a sign of a bad pressure switch. The computer primes the system, car starts, then looks for the psi from the sensor, if it's to low it cuts fuel again.
Not likely. If the F-bodies are set up like the pickups and like my Luminas, the oil pressure switch cannot STOP the fuel pump. It can run the pump if the fuel pump relay fails. The fuel pump relay is energized based on the ECMs priming function (2 seconds) when the key is first turned on, or based on receiving an "engine cranking/running" signal from the distributor.
Low oil pressure cannot turn the fuel pump OFF if the ECM, wire harness, and fuel pump relay are in good condition.
If the ECM is working correctly as I stated, if the ECM gets a low reading from the sensor it cuts the pump. The ECM cut the pump not the sensor. This is for emergencies such as a wreck or rollover so the pump doesn't keep pumping fuel after the engine shuts off so it's not pumping fuel into a potential fire.
Why do you think people suggest the pressure sensor on efi cars as a potential problem when the car won't stay running.
If the ECM is working correctly as I stated, if the ECM gets a low reading from the sensor it cuts the pump. The ECM cut the pump not the sensor.
I can't confirm or deny this as I don't have an F-body service manual.
Originally Posted by Wife'sCar
This is for emergencies such as a wreck or rollover so the pump doesn't keep pumping fuel after the engine shuts off so it's not pumping fuel into a potential fire. Why do you think people suggest the pressure sensor on efi cars as a potential problem when the car won't stay running.
That's not something I've heard suggested.
The fuel pump would quit running when the engine quits running, because there's no distributor signal, therefore the ECM will stop energizing the fuel pump relay.
If the ECM is working correctly as I stated, if the ECM gets a low reading from the sensor it cuts the pump. The ECM cut the pump not the sensor. This is for emergencies such as a wreck or rollover so the pump doesn't keep pumping fuel after the engine shuts off so it's not pumping fuel into a potential fire.
Why do you think people suggest the pressure sensor on efi cars as a potential problem when the car won't stay running.
This is wrong. The switch is wired in parallel to the fuel pump relay supply to the fuel pump. The pressure switch is purely there incase the relay fails your car will still start. Pull the relay and the car will still run, ecm does not "sense" what the pressure switch is doing. it sends power to energize the relay on one terminal and then power to the fuel pump itself on another. check the prints. How would a fuel pump keep pumping on a roll over when the pick is at the BOTTOM of the tank?
Also, how do you know the OP doesn't need a new pressure sender? First sign of a oil pressure gauge fluctuation I would confirm the gauge is OK and test with a mechanical handheld gauge.
On my 87 Z28, my oil gauge starts out normal around 30-40 and then once it warms up it slowly starts dropping. Then is bottoms out
at zero, come up a hair and then goes crazy bouncing all over the place. I changed my sending unit twice (located by my distributor)
but still experience the same issue. Am I changing the right part or of what I read, is there another near my oil filter?
On my 87 Z28, my oil gauge starts out normal around 30-40 and then once it warms up it slowly starts dropping. Then is bottoms out
at zero, come up a hair and then goes crazy bouncing all over the place. I changed my sending unit twice (located by my distributor)
but still experience the same issue. Am I changing the right part or of what I read, is there another near my oil filter?
I would suggest checking with a mechanical gauge. If it is OK with that then it is likely the oil gauge in the dash, there aren't any other parts to fail in the system really. Gauge, sender, oil pump and the bypass spring. It is possible the pump spring is worn out
On my 87 Z28, my oil gauge starts out normal around 30-40 and then once it warms up it slowly starts dropping. Then is bottoms out
at zero, come up a hair and then goes crazy bouncing all over the place. I changed my sending unit twice (located by my distributor)
but still experience the same issue. Am I changing the right part or of what I read, is there another near my oil filter?
Look and see. On the early TBI pickups, the sensor by the oil filter drives the gauge, the switch by the distributor is tied into the fuel pump circuit. Other vehicles are wired differently.
Originally Posted by scooter
I would suggest checking with a mechanical gauge.
Very good advice.
Originally Posted by scooter
it is likely the oil gauge in the dash, there aren't any other parts to fail in the system really. Gauge, sender, oil pump and the bypass spring. It is possible the pump spring is worn out
You forgot the wire harness that ties it all together. A grounding harness will make the needle bounce all over as it randomly grounds on "whatever" metal is nearby.
I've never seen a worn-out pressure relief spring. Never seen a broken one, either. I'm not saying it couldn't happen, just that it's going to be very rare. I have heard of oil pump pickup tubes falling off the pump, so that the pump sucks air at random times. I have heard of pressure relief valves that have stuck open, so when the oil warms up, too much is released by the relief valve and the pressure drops.
If you start by verifying the actual pressure with a proper gauge, you'll know if the engine cannot generate appropriate pressure, or if it has proper pressure but the gauge system is goofy.
You forgot the wire harness that ties it all together. A grounding harness will make the needle bounce all over as it randomly grounds on "whatever" metal is nearby.
This is good advice, but I would think the other needs would also act erratically, since they are all tied together at the cluster. Though I guess it could be that the screw in the back of the cluster for the oil pressure is slightly loose, and that would make only that gauge act erratic
06-29-2015, 10:27 AM
