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wont start when hot outside????

08-13-2007, 06:09 PM
allright guys. This is actually a Tahoe question but it has the same engine as us silverado fellas. For two days in a row when it was over 100 degrees here my friends Tahoe would not start. This is what we did though opened the hood and let air blow across the ingine for about twenty min. then it would start. But we also had the drivers door opened the whole time to so I guess the computer getting to hot could be thrown in there to. Before cooling it down it would only fire one time and quit. The trouble maker is an 03 with a 5.3 in it. And it was about 105 110 out when we tried to start it. (it was sitting in the sun to)
Appreciate all inputs

08-13-2007, 07:02 PM
Basic stuff here did you have spark and fuel pressure?

08-13-2007, 07:34 PM
well we thought maybe there was to much pressure on the gas tank being hot outside so we opened up the cap but didnt help. It would fire one time and die so I don't know if it quit sparking and died or what. We didnt pull a wire off to see if it was or not. All we know is that we are sure it is heat related cause the first time he let it sit till night and started right up and then the second time we just had the hood up and doors open then mysteriously started. Hasn't had a problem in the last 3 days now and temps are lower so thats whats making me think heat.

08-14-2007, 07:05 AM
Check the fuel pressure.

08-15-2007, 10:11 AM
could be the Fuel Pressure regulator.

08-15-2007, 02:05 PM
Leaving your door and hood open didnt crank your truck, and the computer is under the hood.

First thing I think of is:

After trying to crank it a few times will let the fuel pump prime to pressure. Its possible that the first several cranks didnt prime enough. By design the fuel pump is to hold pressure but they can leak pressure back into the tank or an injector can leak into the cyl when off, also causing the fuel pressure to drop below crank level.

Get a fuel pressure gauge. Before you turn the engine off attach it and let it sit. See if the fuel pressure drops after it sits a while in the heat.

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