Question about 2000 GMC Safari

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2000 safari starting problems when outside temp is below apx 75/80 degrees F

My 2000 GMC V-6 CFSI (Engine code "W"), safari immediately starts and runs great but only when the outside temp is above 75/80 degrees F. (Note sometimes when it starts on a warm day the engine will run a little rough for about 10/15 seconds)
But when the outside temp goes below 65/75, it will crank just fine but will not start at all. I can hear the fuel pump priming so I think that it's okay. I have replaced the fuel pump relay, Mass air flow (MAF) sensor, and the " intake air temperature sensor" (IAT) located on the engine air intake duct attached to the air filter housing. Is there something else that might keep it from starting on cool days. Is there anything in the Vehicle control module that would cause this?

Your help would be highly appreciated.

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  • RICKSLM Oct 25, 2008

    Yes it is a 4.3 l

  • RICKSLM Oct 25, 2008

    Yes sonic2552 it is a 4.3l

  • RICKSLM Oct 25, 2008

    Service lite is not on. Replaced sensors becaused they both had thermistors (temperature sensitive sensors) based on info from a Haynes repair manual. I thought they might be affected by outside air temp.

  • RICKSLM Oct 25, 2008

    I've used the dry gas already that didn't help. But I will try your other recomendations tomorrow. Thank you!



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There is a much richer fuel mixture during a cold start, the colder the engine the richer the fuel mixture
retarded ignition timing causing the fuel to burn for a longer period of time makes the engine heat up faster
anything that doesn't allow the mixture to be properly metered, like vacuum leaks, bad temperature sensors, or O2 sensors, MAF or MAP sensors, bad EGR valves or PCV valves hoses or tubes,
and or
anything that will cause the fuel mixture not to burn properly, like worn spark plugs, or any other ignition part, wires, cap, rotor, timing, compression, will cause poor start or no start conditions that are worse in lower temperatures,
also low voltage, week battery, slow cranking of the engine can also cause hard to start conditions

Posted on May 20, 2016

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Also check fuel pump pressure and make sure it is over 60psi i had a weak one and even gm dealer said it was ok but i had same problem and finally changed pump and voila no more failed starts

Posted on Nov 16, 2008

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Is this a 4.3l

Posted on Oct 25, 2008

  • Anthony DiVeronica Oct 25, 2008

    is the service engine light on at all... why did you replace the sensors described above.

  • Anthony DiVeronica Oct 25, 2008

    well there are a few things to check. remove the air cleaner assy and look into the throttle body, open the throttle plate and look... if you see brownish resin then your IAC (idle air controller) could be stuck, i recommend cleaning the throttle body with some carb cleaner. also check your battery connection... it may crank fine but the pcm in a gm vehicle is very sensitive, a small amount of corrosion could cause this problem. you may also want to try and put a bottle of dry gas into your fuel tank just to be safe.


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