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Hello everyone. So, recently I went round and round about my fuel pump not working properly and replaced fuel pump, fuel sending unit, fuel filter, fuel pressure regulator, then ICM, ignition coil, then finally opti and she came to life. Now..... I am getting a "Low Oil Level" light and the car shuts down for 1/2 a second. Couple of things.....

This only happens once a trip. Meaning if I run to the Wawa itll happen once that trip, if I run across town itll happen once that trip, etc.

From what I read it seems like this would be the Oil Pressure Switch. But heres the thing, i have an oil gauge using that port, have not had an Oil Pressure Switch for easily 15 years.

So, if there a work around for this? Do I twist a few wires together at the connector to make it think its working? Maybe thats what I did a long time ago when I installed the oil gauge but I can not remember since its been so long.

And yes, I absolutely positively have plenty of oil in it, thats the first thing I checked.

Thanks for all your help guys!
 

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I'd probably try the oil level switch and it's associated wiring/connectors.

I don't know if it's normally open or normally closed, but should be easy to test out. The connector on the oil pan is "poor" at best and has little environmental protection so that's the first place I'd look.

The brown/white wire (Low Oil Level Control) goes to the dash and the low oil bulb. I'm assuming the PCM sees the switch change state and cuts the engine out accordingly, but since it's an intermittent thing, it recovers right away and you can keep going.

 

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Matt

My understanding is the OP sensor (top rear of block) was what shut fuel off when it reads 5 PSI or less. Anyone please correct if my understanding is wrong....IDK if the "oil level" sensor is also something the PCM sees and will shut fuel off when oil is low but Fix Until Broke notes wiring to check if it does. That oil level sensor connector you need a small screwdriver to lift the lock tab to remove it.

Maybe the float arm of the oil level sensor is just stuck/sticking and you need a new sensor

I also have a OP gauge but I used the port above oil filter adapter and maintained the factory oil pressure sensor as is
 

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My guess is that the PCM would do something with the oil level signal, otherwise it would be like the low coolant or low washer fluid switches and go directly to the instrument cluster?

Maybe it's a combination thing where the PCM is looking at both the oil level and pressure signals - as long as there's oil pressure, if it sees low oil level, it will turn the light on in the dash.

If the oil pressure is low/missing and the level is ok, it ignores it and keeps going until the level is not ok and then turns the engine off

I'm just guessing here - My FSM is not here to take a look at the theory of operation.
 

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Since the OP keeps opening new threads I had a look back over his post history. For other here is a summery of things that might be related.


This seems to be a T-56 car so the engine and definitely the transmission wiring harness have been disturbed.


Oil leak at filter area.
https://www.impalassforum.com/vBulletin/34-engine-problems-maintenance/229574-oil-leak-filter.html


ICM and coil in 2010 and 2012 The 2012 post suggests both were done before?
https://www.impalassforum.com/vBulletin/34-engine-problems-maintenance/250925-need-help-bad-please-help.html
https://www.impalassforum.com/vBulletin/34-engine-problems-maintenance/269641-think-i-blew-up-opti.html


Replaced Sending Unit, Fuel Pump, and Fuel Filter, still same issue.
We can add Fuel Pressure Regulator to the list. Swapped that out this morning and no change unfortunately.
Yep, sorry, I didnt list that. Did swap the relay.
Matt M
https://www.impalassforum.com/vBulletin/34-engine-problems-maintenance/1316568-intermittent-fuel-pump-issues.html


Ok, we can add Ignition Coil, and Ignition Coil Module to the list. Just changed those out and same situation.
ANNNNDDDDD......It was the Opti!
Thanks for all the help everyone, shes back on the road!
Matt M
https://www.impalassforum.com/vBulletin/34-engine-problems-maintenance/1316586-update-my-intermittent-fuel-pump-issue.html


Except it did not.


This is just a continuation of the same issue(s) from your other thread. IDGet it. The history and continuity there can only help chase down your problem. If you're asking for just electrical suggestions here, then without going back to that other thread it'll be important to know what electrical diagnosis you've tried so far. As mentioned above the IC, ICM and opti (and grounds) are instant targets.
96 Black


That sounds like it comes under the heading of SWAG (Scientific Wild Ass Guess). Although, the symptom of happening when another system was activated leads one to commonalities, and making sure they are in good condition. Electricity is funny, if its ground route is disrupted, it often finds another path to ground. This can cause strange symptoms, or interactions with other systems
.Fred Kiehl


Now..... I am getting a "Low Oil Level" light and the car shuts down for 1/2 a second
. Matt M


The ECM will not stop the car for a low oil condition, it simply tells you
ShudahadaV8


Based on my years of experience with these cars, this sounds to me like the infamous resolution signal failure from the opti. The Low Oil Level light is a red herring. The opti contains two resolution signals, low and high. If the high resolution signal fails, it will cause a stumble or a stall. But will re-fire since the computer will compensate by reverting to using the low res signal until the problem clears. There is a bug in the PCM that will also illuminate the Low Oil Level light when this happens for a moment. I've seen this happen every time an Opti resolution signal drops out. If one of the signals have a bad connection, it will also cause a hard start as a result. Then maybe next time, the signal resolves itself and all is well. For a while. Until it drops out again. And the big stumble/stall repeats along with the Low Oil Level light. And a hard start.

That being said, there are two connectors between the Opti and the engine harness. The first is at the Opti itself. This is the loooong connector. Unplug it and clean the 4 female metal contacts as best you can. It's hard to get inside those. Sometimes a straight pin can be used to dig out any crud. Look for any oil sludge or corrosion in there. If there is any, it's best to replace the harness. Repeat this for the other end of the harness where it plugs into the engine harness.
Storm9C1


I am going to summarize from the 94 FSM 8A-82-16 Instrument Cluster Chevy Circuit Operation “low Oil Level” indicator.


The PCM will not check for a low oil condition unless the drop in engine coolant temerature corisponds with the chart since the last ignition “OFF” Basically the PCM only will light the “LO” if the car has be off AND the engine has cooled off a bit. It will not light the “LO” while the car is running. If the “LO” comes on because of a low oil condition IT WILL STAY ON (EVEN IF OIL IS ADDED) FOR THE REST OF THE CURRENT IGNITION CYCLE. Your problem does not seem to match a low oil problem.


From what I read it seems like this would be the Oil Pressure Switch. But heres the thing, i have an oil gauge using that port, have not had an Oil Pressure Switch for easily 15 years.

So, if there a work around for this? Do I twist a few wires together at the connector to make it think its working? Maybe thats what I did a long time ago when I installed the oil gauge but I can not remember since its been so long.
Matt M.


You are confusing the “LOW OIL LEVEL” switch in the pan with the OIL PRESSURE switch in the block.



You need to explain what you did to the “Oil Pressure” switch. It keeps the fuel pump running IF there is oil pressure.


Without the “OP” switch keeping the fuel pump on from the 94 FSM 6E3-A34 Pump relay circuit:It will (the fuel pump) remain “ON” as long as the PCM is receiving low resolution reference pulses from the OPTI:


So if the OPTI low res does not get to the PCM the engine slows down and oil pressure drops, and the fuel pump stops, AND/OR the PCM stops the fuel pump.

from the 94 FSM 6E3-A34 Pump relay circuit:Improper fuel system pressure will result in one or all of the following symptoms:
Cranks but won't run
Cuts out, may feel like ignition problem
Hesitation
ECT.


Get a scanner or logger and monitor the OPTI low res signal. Or use a Volt meter to monitor the Fuel pump. You could stuff a very small wire into the relay socket then plug the relay back in.



Are you OBDI or OBDII your history looks like you may have switched at some point?
 
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