Question about 2000 GMC Safari
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.
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,
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
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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