How can oil pressure sending unit affect fuel switch 4.3 engine 92 gmc pick-up?

An oil pressure sending unit cannot directly affect the fuel system or a fuel switch in a 4.3L GM engine (or any engine for that matter). They are completely separate systems. The oil pressure sending unit monitors oil pressure and sends a signal to the gauge; the fuel system deals with fuel delivery.

If you're experiencing fuel-related issues *concurrently* with an oil pressure problem (such as a faulty oil pressure sending unit giving a false reading), it's purely coincidental. The issues are unrelated, and addressing the oil pressure problem won't fix a fuel problem, and vice versa.

If you're having fuel issues on your 1992 GMC pickup with a 4.3L engine, the problem lies elsewhere. Possible causes include:

* Fuel pump: A failing fuel pump is a common culprit.

* Fuel filter: A clogged fuel filter restricts fuel flow.

* Fuel injectors: Clogged or faulty injectors prevent proper fuel delivery.

* Fuel pressure regulator: A malfunctioning regulator can cause incorrect fuel pressure.

* Wiring/connections: Faulty wiring or connectors in the fuel system can interrupt power.

* PCM (Powertrain Control Module): The PCM controls many aspects of fuel delivery; a faulty PCM can cause significant problems.

* Fuel switch itself: The fuel switch could simply be malfunctioning.

In short: Fix the oil pressure issue separately (if there is a genuine problem, not just a faulty sending unit). Then, diagnose and address your fuel system problems independently. They are not related.