Low Oil Engine Shut-off

[hookem_9]

I'm looking at buying a GMC Sierra repairable which was rolled on it's side. What I'm concerned with is, did the engine shut off soon to cause no damage or? Does the computer have logic to sense low/no oil and shut down?

Thanks,

 

Hookem

[mcreyaufmiller]

There should have been a inertia switch in the truck somewhwer to shut down the motor when it was on it's side.

[GMCTech]

When oil pressure reaches near zero psi the fuel pump cuts off. So after oil pressure is lost it will only run a few seconds.

 

Hope this helps.

[GM-Tech]

I'm not so sure the fuel pump is shut off when oil pressure is zero. I can't find anything that says that.

 

That was a common misconception on the older vehicles that used the oil pressure switch directly to supply power. It was really just a backup to the relay. If oil pressure dropped to zero on those, the relay still kept the fuel pump on. If the relay failed, you could crank it long enough to build oil pressure and get the vehicle started. Of course in that case, if oil pressure failed, it'd quit with no working relay to keep the pump on.

 

On the newer vehicles, the oil pressure switch is an input to the PCM. So it's possible that when the PCM sees zero oil pressure, it turns off the fuel pump which it controls. I just can't find that in writing anywhere. It would seem the smart thing to do, but they don't always do the smart thing. Guess I'll have to disconnect an oil pressure switch at work and induce a zero reading to see what happens.

 

There's definitely no inertia switch. That's a Ford thing I believe.

[chevroletmb]

When oil pressure reaches near zero psi the fuel pump cuts off. So after oil pressure is lost it will only run a few seconds.

 

Hope this helps.

 

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i'd like to know where u got that information.

older trucks used to run power to the fuel pump through the oil pressure

switch to allow for the fuel pump to power up once the engine built up enough

oil pressure in the case that the fuel pump relay was bad.

but i don't think the nbs trucks have system.

regarless only if the relay was bad would the fuel pump shut off once the engine lost oil pressure.