Alright here we go...

I changed out the fuel filter last night and engaged the pump while the filter was disconnected. Yes, the fuel pump is pumping gas.

After putting everything back together I put a fuel pressure gauge on it. It read somewhere between 20 and 30 PSI when iginition turned to on (2 second fuel pump engagement). So, that tells me that I will be replacing the fuel pump next. Yeehaw!!

 

I just replaced mine. Not too bad. Takes a couple of hours, plan for half a day if you have never done one before. Read this thread, I put some tips in my last post. https://blazerforum.com/m_4651/tm.htm

No the S-series Blazers do not have a fuel cut off switch. However I do believe they have a roll over valve. Pretty sure it is that black box all the fuel lines run into. I have only seen a reference to it in the Chilton/Haynes manual.


Oil pressure switch tells the pcm if the engine has oil pressure. The pcm will wait a few seconds before using that info to kill the fuel pump and stop the engine. The only time the engine will have oil pressure is while it is running, and the oil pump is pumping oil. So when you start the engine, it doesn't have any oil pressure. Clear as dirty oil? [&:]

 

I replaced the fuel pump and the car started right up, had to jump start it. Starts and runs every time since. I know we used to be able to hear it running or a whirring sound from that general area while the vehicle was running. Now I don't hear anything like that while the car is running. So I conclude that the fuel pump finally bit the dust. I haven't checked the new pressure with a gauge, but the truck actually starting when before it would not tells me it must be pressuring the injectors to the correct psi. I will look this weekend just for kicks though...