I have a 95 4 door, 4.3 Vortex. I went out to start it and it cranks over but its a no start. The relay clicks but the service engine light stays on and the check guages stays on also, as I have been researching this problem, I'm thinking thats its the oil pressure switch can anyone give me any Ideas on how to test the switch? and where is it located? I have a hanes but it is not specific on the location or how to test it, it just says that if the oil pressure drops below a certain level it will cut the pump. Thanks in advance for any help......

 

The oil pressure switch should only cut the fuel after the engine is started. When you first turn the key to "on" you should hear the pump run for a few seconds to get up to pressure then it will stop. If it isn't putting out enough pressure it won't start. Do a fuel pressure test-autozone has loaners. Also check the filter, they can cause the pressure to be below specs if it is clogged.Also check the fuel pump relay.