How does low oil pressure turn off the engine, what's the sequence of events?

 

this isnt just any v6 site. 4th gen camaros dont have a low oil pressure shut off. lol, we have a check gage light.

 

I thought the fuel pump ran the power thru the oil sending unit. I know they did on the older Tune port systems.

Driving a car at zero oil pressure always damages the motor. There is no way to predict how long it will be before that rod bearing will spin.

If you PCV valve is failing that will let the oil into the intake like you described but if the PCV valve is working and oil is getting in the intake that would indicates that there is to much blow by for the ventilation system to handle and the pressure is backing up into the intake. Pull the oil cap with the car running. Is it pushing air out?

 

thats to make sure the fuel pump stays on. lol.

 

I'm talking about v6fbody and GM 3800 websites, not just any V6 site.

 

Regardless, the F body doesn't have a low oil pressure kill switch.
What Gorn was referring to is what 3rd gen's had, a secondary power supply to the fuel pump that ran thru the oil pressure switch. That was to keep the pump running should the relay (main supply) fail, but many mistakenly think it was to kill power to the pump if the pressure drops off.
Below is a schematic for a 98 f-body. I'm not seeing a secondary supply like the 3rd gen schematics do show, nor do I see a kill switch. Maybe somebody would be kind enough to unplug their oil pressure switch while the engine is running and let us know what happens.

 

Ok i spent about an hour researching this because I remember a GM teacher telling me that the reason for the power going thru the oil sending unit was in case of a crash. Seems I was not the only GM tech that was taught this. The fact is the fuel pump power going thru the oil sending unit is a saftey item but not for shutting the car off. It is to keep the car running. If you where crusing at 70 MPH and you fuel pump relay would fail the car would shut off. This is a safty hazard. So to be sure that does not happen they run a power thru the oil sending you so you can continue to drive. If everything works an the relay fails you will get a check engine light and the next time the car turn off it will not restart.

Fuel safety is done by ECM/PCM. It will turn off the fuel pump 2 seconds after the motor stop sending a crank signal. GM has no system in our cars that will shut the motor down due to oil pressure.

To the original poster. Your motor shut down do to lack of oil? You are luckly it still runs and there is not way to predict how long it will hold together. I would not put a penny in fixing that motor. One of the main jobs of oil is to carry heat away from places coolant can not get to. The pistons and exhaust valves will be heavly scored. I have pulled enought of these motors apart to know in most cases it is not worth fixing unless you planning a complete high dollar rebuild. Go pick up a used motor that has not run dry of oil and work from there or get a plan inplace for when the motor sieze up. It is coming.

 

Yep, that's what I was saying. Oh, shame on your GM teacher, he's probably the one who started that whole safety kill urban myth!
With a failed relay, I think the engine would still start once the engine is zinging over enough to build up oil pressure. The relay power supply and oil pressure supply to the pump were two separate parallel lines.

 

I will have to check my history at home to see if I can find that thread again. There was 3 different techs that said they got that training also. I wonder if they where all from the GM tech center in Pittsburg PA. Cause that is where I picked it up. It would be funny if one guy caused all this confustion.

 

Well....if it came from a GM tech, it must be true. Pass it on. lol