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2001 Chevy Tahoe Weird Starting

Tiny
REDSNOOK
  • MEMBER
  • 2001 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
I have a 2001 Tahoe with 170K miles. It has been a great truck but lately it started not starting easily under specific circumstances. It starts great, first try, whenever the engine is cold. If you run it allow it to get to normal running temps then shut it off, then start it again within 5 minutes or so it starts fine, but if you wait longer, it doesn't want to start unless you turn the key (not to start just to turn the electric on) then wait 5 seconds then it will start. If you get in the car and just turn the key it takes three tries before it will start unless it has had time to cool all the way down.

Since the issue has begun, I have: Cleaned the K&N air filter, changed battery, changed the plugs, changed the plug wires, changed the fuel filter, changed the fuel pressure regulator, changed the pcv valve. None of this has helped.
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Sunday, November 9th, 2008 AT 9:21 AM

11 Replies

Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
When the "no start" condition exists, and you turn the key to "on" do you hear the fuel pump run?
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Monday, November 10th, 2008 AT 6:24 AM
Tiny
REDSNOOK
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  • 5 POSTS
Yes the fuel pump runs when the key is turned.
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Monday, November 10th, 2008 AT 12:37 PM
Tiny
REDSNOOK
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  • 5 POSTS
I noticed today, if I turn the key, not trying to start three times when it is "in a not starting situation", it will start after turning the key three times.
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Monday, November 10th, 2008 AT 1:53 PM
Tiny
JAMES W.
  • MECHANIC
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I know it's not a professional thing to say but, this is crazy. The only things that are happening when you turn the key to "run" are, the fuel pump will run for a few seconds, and plus voltage will go to the ignition module. The plugs and injectors won't fire until engine "crank". We need to go back to basics which are; when the no start condition exists, are you missing spark, fuel or both. Without knowing this I'm just guessing, and guessing gets expensive. I haven't ruled out ECM but, that doesn't make sense either. If you can get this information it will help narrow it down. Also, if you can check injector pulse too. You can do this with a regular test light between both terminals of any injector connector. Let me know what you find, Jim.
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Monday, November 10th, 2008 AT 7:21 PM
Tiny
REDSNOOK
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  • 5 POSTS
Just thought of something. Could dirty injectors be causing this? Tahoe has 170K and never had them cleaned. If so which do you recommend, on or off car?
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Tuesday, November 11th, 2008 AT 10:23 AM
Tiny
JAMES W.
  • MECHANIC
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You will usually notice a dirty injector problem at idle not on startup. I have never seen all the injectors plug at once. If this would happen the car wouldn't run at all. Dirty injectors usually start out with one or two and act like a missfire at idle or on acceleration. If you want, you could use an fuel additive injector cleaner, but I have never seen a "miriacle in a can" that really worked. You usually wind up changing injectors. To reiterate, If you can check spark, fuel pressure or injector pulse loss, or any combination thereof, it will help us track it down. Jim
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Tuesday, November 11th, 2008 AT 12:11 PM
Tiny
REDSNOOK
  • MEMBER
  • 5 POSTS
Ok, it has to do with the fuel pressure. When the car won't start but you keep cranking the pressure creeps up slowly then pops up to 57psi and it starts. If you don't try to start but just turn the key under the "hot - not going to start situation" the pressure doesn't come up right on the first turn of the key, on the second one it does and then it will start. When you do this when the engine is totally cold it comes up to 50 psi and starts. When the engine is running the psi is at 48 psi. I have spark so thats not it. The noid light kit that I purchased did not have the correct light in it so I haven't been able to check that yet, but I think that isn't an issue given the fuel pressure issue.
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Thursday, November 13th, 2008 AT 8:37 PM
Tiny
IMPALASS
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  • 3,112 POSTS
Hello -

I see Mr James R. Weizel is doing a great job assisting you and will follow up. I have provided the fuel pressure. You didn't specify, but both the 4.8L VIN L and the 5.3L VIN T, which ever one you have is Key on, engine off, 55-62psi.

I would say your fuel pump is going out but since Mr Weizel has been reviewing this provide him time to respond since he has the back ground.
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Thursday, November 13th, 2008 AT 8:59 PM
Tiny
JAMES W.
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Let's try a little experiment. ImpalaSS gave me this idea when I read his posting. When you're in the situation where the vehicle normally won't, disconnect the fuel line from the pressure regulator and point it into a coffee can or something to catch the fuel. Obviously, being careful, we don't need a fire. Then, turn the on/off like you would normally, 2 or 3 times and see if the fuel flow starts out slow and on 3rd or 4th try it has increased. One more thing, before you do any of the above, as soon as you have turned the car off, go around and crack open the fuel cap and see if you have any "vacuum" there. If no, then go ahead with the flow test. If yes, Try driving it around for a while with the cap lose. Keep me posted. Jim
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Thursday, November 13th, 2008 AT 10:09 PM
Tiny
IMPALASS
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I attached info on the fuel system for your review redsnook.........

While I am here, just a couple of other things to throw out for brainstorming.

1. When you say you have spark during these 3 times, you have pulled the plug wire say on the 2nd try and you have a strong, blue, popping spark?

2. Next, fuel pressure is still a little low to me..... It may jump to 57 but you said running it is 48 and it should be 55-62 key on, no engine running... It may be dropping fuel pressure internally when it warms up and starts working after sitting.

3. How about the fuel relay working intermediately? When it's cold, it's fine. But sticking or getting warm when running?

4. Really dumb question... How much fuel is in the tank? There is a TSB on no crank due to the gauge being off.

I wonder if it is a fuel pump and relay but I am very interested to see the test that Mr Weizel is having you do.
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Thursday, November 13th, 2008 AT 11:52 PM
Tiny
IMPALASS
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Redsnook

Is this a 4.8L VIN L or the 5.3L VIN T, and do you have one or two tanks
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Thursday, November 13th, 2008 AT 11:55 PM

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