Mechanics

CHEVY TRUCK WILL NOT START IN COLD WEATHER

2000 Chevrolet Silverado

Engine Mechanical problem
2000 Chevy Silverado V8 Two Wheel Drive Automatic 191000 miles

Ok here is the situation. I have a 2000 Silverado 5.3L with about 191,000 miles. The problem I am having is that the truck will not start when it is very cold outside (below 30 F). When attempting to start the motor turns over great but never fires up, after about 5 min. There is a " thud" like sound immediately after I let off the key, not very loud, but noticeable. After continuing to try to start (about 15 sec at a time) finally after about 10 min or so it will start and run beautifully like there was never a problem. The only time this happens is on the first start of the morning when it is cold, after that it starts every time, runs perfect. I don't understand
I took it to the dealer and they told me it was most likely the intake gasket, I replaced it, same problem. Then I was told it was the fuel pump, replaced it and the filter, same problem. Then was told it was either the gas or anti-freeze freezing, now I'm running 97 octane w/ Sea Foam and anti-freeze rated at -41 F at about 75% mix, and I'm still having the same problem. Any thoughts or input would be greatly appreciated.
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Jamiedallen0481
January 6, 2010.




Try spraying ether into the throttle body when the problem is present. Does it then start and run for a few seconds or so.

IF so check your fuel pressure regulator for leakage, The 5.3s had a problem with this condition. Sometimes you would get a raw fuel scent under the hood that helps shed light.

IF this doesn't pan out, the nect two things I would check for is first fuel pressure that HAS to be in spec.

And check for spark presence with a spark tester.

Post back if this doesn't get on on track and we can go from there.

(BTW what brand of fuel pump? Seen way too many aftermarket problem childs. About the only one I trust anymore is a delphi. I think the connectors are suppossed to be changed at the same time on those.)

How would you go about checking the fuel pressure regulator? Sometimes when trying to start it it will run for a second at the most and die, not slowly but very suddenly, basically just fires and revs and gone. The fuel pump was either AC Delco or Delphi, it was the OEM and I did have to change the plug.
Thanks
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Tiny
Jamiedallen0481
Jan 7, 2010.


http://www.2carpros.com/forum/automotive_pictures/30961_fpr_1.gif



#9 is the regulator, pull the cover off and look on the rail.

Did you try the ether?

Of all the things you replaced, the only thing I questioned was the fuel pump. Didn't they check fuel pump pressure before replacing it? That would have told them it wasn't the problem.

As far as the problem, has the check engine light come on? Also, I need you to check something for me. When the engine is cold and doesn't start, I need you to see if it is getting spark and fuel to the engine. Here are the how to's for that.

http://www.2carpros.com/how_to/how_to_test_an_ignition_system.htm

http://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

If both check out good, I would say replace the temp sensor. It is what tells the computer how rich to make the fuel mixture based on outside temp and coolant temp. Basically, it has taken the place of the choke on the old carbs.

Let me know what you find.


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