GMC Repair: Electrical, gmc 1500, gas cap

Question
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Followup To
Question - Yes ,you can hear it run then shut off as it should.The book I have states fuel pump pressure should be 60-66 lb do you agree with this I haven't had time to check pressure yet ,but I will post to you what I find,if you have other thought's ,I do appreciate your help.
Allen
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Followup To
Question - That's the whole thing I haven't done anything ,or had any problems,no repair of any nature.As for the starting thing if you get in turn key it will not start ,you can run battery down and it won't start,but if you turn key and let off quickley it will start everytime,could fuel pump pressure be to low ,I have not checked this.
Thanks
Allen
I have a 1997 GMC 1500 5.0 It does not want to start unless I hit key and let off quickley ,like starting circuit is robbing impulse to coils,after it finally starts it runs fine ,I have a code reader and have tried various ways to make it set a code but reads clear ,it is a very strange problem that I have never encoundered before,changed cap,rotor,plugs
no help (didn't think it would ) it's some kind of glitch hope you have encountered before.
Thanks
Allen
Answer -
I have seen many odd things over the years.

What was the LAST repair on the vehicle ?. ANY repair of any nature ?. In most cases problems that arise days, weeks or even months later can usually be traced back to the previous repair.


Please explain your statement : "hit key and let off
         "quickley.

I need more detailed info on the above.

autohelp
Answer -
OK, Let's do a simple HEARING test to hear if the fuel pump is operating correctly.

This requires TWO people:

1. Remove the gas cap at the fuel tank.

2. Have you or your helper listen at the gas cap opening.

3. Turn your ignition key to the ON position ONLY, Do NOT
  attempt to start the engine.

4. Just as you turn the key to the ON position you or your
  helper at the gas tank should hear the electric fuel
  pump run for TWO seconds and then STOP.


DOES IT ?.



autohelp

Answer
Could be fuel pump.
Could be fault in the ignition switch.
Could be fault in the ignition module.
Could be fault in the ECM.
Could be fault in the wiring.
Could be leaking fuel injector(s).
Could be faulty fuel pressure regulator.
Could be faulty fuel rail.

Lots of COULD BE'S, Needs to have all systems TESTED to find exact cause.

This problem is NOT unique, I have seen it many times but to put the finger on the most common FAULT can't be done as it could be anything.

Just for fun try something for me:

Next time you know this is going to happen:

Turn the ignition to the ON position, Do NOT try and START the engine, just turn the key to the ON position then back to the OFF position THREE times and then see if it will start right up.

let me know.


autohelp