like an idiot, I ran out of gas. when I added gas to the tank, via a gas can, 5 gallons, the engine turns but will not start. I know thyere is gas in the tank. Any hekp is appreciated. 2004 2 dr ls

 

Cycle the key on for several seconds - then off for several seconds. Repeat maybe 5 times before trying to start again. Fue pump works for 2 seconds when key is turned on and then should not come on again until engine has oil pressure. If no start, then check fuel pressure at the Schrader valve behind the throttle body when the key is first turned on and go from there. You can borrow fuel pressure gauge from Autozone or Advance Auto Parts for free (with deposit).

 

I agree, check fuel pressure like Les mentioned. The pump should activate for 2 seconds when the ignition is initially turned to the run position. It should run continuously while the starter is engaged, (engine oil pressure has no affect on fuel pump operation).

 

Learned something new today!! ;-) Guess that dates me a bit! What is the crtieria for fuel pump operation with the key in run position (too lazy to look it up right now).

 

some vehicles have button you prss after an accident or if you run out of gas. shuts off the fuel flow. Am I coeect in thinking this is not the case with the Blazer? I know Explorers have on

 

^yup marton its just ford as far as i know that has that.


you ran out of gas and now it wont start? sounds like pump died,if it did. if it did dont buy anything but a delphi or ac delco unless u enjoy doing it ever year.

Buy a can of starter fluid, spray a lil into the throttle body and see if it starts then dies. if so,maybe the pump.

 

Key on engine off, the PCM activates the pump. If the PCM does not receive crank position sensor pulse after ~2 seconds, it deactivates the pump.

Some 4.3L equipped vehicles, (not all) have a circuit in the oil pressure sender that provides an additional circuit to the fuel pump when oil pressure is above ~7psi. The purpose of the circuit is to reduce amperage flow through each wire, essentially doubling the available available current, which keeps the wires cool. Only senders with a grey wire are equipped with the circuit. Back in the 70's and early 80's, the fuel pump circuit ran through the oil sender and deactivated the pump if oil pressure dropped below ~7psi as a safety feature.

 

So, the crank sensor pulses to the PCM is what triggers the fuel pump to work, once past the initial 2 second pulse?

 

Correct.

 

tried the key recyclen 5 times. started right up. Thanks to all of you for your help, For one, it wasn't something major. Thanks again.