Chevrolet Repair: Chevy Blazer starting problems, oil pressure switch, fuel pressure regulator

Question
I have a 1997 Chevy Blazer.  When I try to start it, it would crank over but not start. So I dribbled some gas in the throtle chamber and it starts up.  But when turned off (whether after 5 minutes or 5 hours ) it wont start again. Fuel pump was replaced 1 year ago, fuel filter replaced 2 months ago. Ignition switch, starter, crank position sensor, Fuel pressure regulator, & temp sensor, all were replaced 2 weeks ago. injectors were tested ok on OHMs. They did not squirt when key was turned on (is that normal?) Any clues as to why it won't start easily?

Answer
Hello Robert,
The ECM operates the fuel pump relay for three seconds or so when the key is turned to run. Then, as long as the ecm is recieving a signal from the crank sensor that the engine is cranking over, it will continue to operate the fuel pump relay.

There is another system to power the fuel pump directly, once the engine starts, and that is an oil pressure switch. As long as there is at least 4 PSI of oil pressure, that switch will send power to the fuel pump, weather the ECM operates the relay or not.
That would explain why yours runs after dribbling the gas. The oil pressure builds up, and the oil switch runs the pump, and all is well.

Your problem, then, is that the relay isn't sending power.

That could be because the relay, or a wire associated with it is bad, the ECM isn't sending power to the relay, or the crank sensor isn't sending a signal to the ECM.

So the relay is probably the area where you need to be checking, although the relay itself may not be the problem.

Van