Oil pressure gauge pegged out

[jnt412]

Its possible the oil pressure switch is used to cut power to the fuel pump when low oil pressure is detected.

 

[87ChevyR10]

I finally found mine. It's sitting next to the oil filter. It'll get replaced at next oil change.

 

[chengny]

Its possible the oil pressure switch is used to cut power to the fuel pump when low oil pressure is detected.

I have heard that a lot. It is kind of like that but not exactly. When oil pressure is established, the switch contacts close and supply a backup source of power to the fuel pump. The normal power to the fuel pump is supplied via the FPR when it receives a signal from the ECM. The ECM powers the FPR coil when it senses a pulse from the distributor - indicating that the engine is running.

From what I can gather, this is to aid in cold starts. Those times when the engine is cranking over but no spark has been generated. The ECM does allow for a 2 second period of "no spark" before it kills power to the FPR and stops the pump. If the engine has oil pressure due to cranking power is still supplied directly to the pump through the oil pressure switch:

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So, while oil pressure will allow the engine to start, lack of oil pressure will not kill the engine. The ECM will continue to keep the FPR pulled in and run the fuel pump.

 

[jnt412]

is this the same for a mechanical fuel pump?...

Its possible the oil pressure switch is used to cut power to the fuel pump when low oil pressure is detected.

I have heard that a lot. It is kind of like that but not exactly. When oil pressure is established, the switch contacts close and supply a backup source of power to the fuel pump. The normal power to the fuel pump is supplied via the FPR when it receives a signal from the ECM. The ECM powers the FPR coil when it senses a pulse from the distributor - indicating that the engine is running.

From what I can gather, this is to aid in cold starts. Those times when the engine is cranking over but no spark has been generated. The ECM does allow for a 2 second period of "no spark" before it kills power to the FPR and stops the pump. If the engine has oil pressure due to cranking power is still supplied directly to the pump through the oil pressure switch:

You must be registered for see images attach

So, while oil pressure will allow the engine to start, lack of oil pressure will not kill the engine. The ECM will continue to keep the FPR pulled in and run the fuel pump.

 

[chengny]

No - a mechanical fuel pump is driven by the camshaft and has no external controls. It will deliver fuel to the carburetor whenever the engine is rotating.