Why is my vehicle sputtering when turning over the ignition after filling up the gas tank to full?
Asked by CR Mar 24, 2014 at 04:17 PM about the 2007 GMC Sierra 1500 SLE1 Crew Cab 4WD
Question type: Maintenance & Repair
Truck has trouble starting after filling gas tank to FULL. It will start but ,sounds like its
sputtering and struggling to start. After starting the truck, it will run great until its next fill
up and the same problem will occur. Sometimes it takes two tries by turning the key over
in the ignition to start the engine. If I fill the truck up to 3/4 of a tank it will have no
problem starting.
3 Answers
It sounds like something is amiss with the evaporative control system, which manages fuel vapors from the tank. I would guess that excess vapor, or maybe even liquid fuel, is finding its way to the engine and over-richening the mixture. When filling, you should let it automatically click off and stop right there. Adding fuel past that point has no real benefit and gets liquid into areas that are designed to deal with vapor. If you happen to be overfilling it (past the click-off), that might be exacerbating the problem, and it's conceivable that ceasing to do so might alleviate the symptom. You may find you can "work around" the symptom by holding the accelerator pedal to the floor when starting after a fill-up. On most vehicles, this enages "anti-flood mode" by shutting off the injector activation. The sure fix, though, would be to have it tested and repaired by a competent auto repair facility.
Thanks for the reply. I have over filled a few times not realizing the consequences of trying to get another litre in the gas tank. I had the truck tested and the there was three codes diagnosed: p0466 (EVAP vent control problem, p0455 (EVAP system large leak), and p0496 (EVAP system flow during non purge).
I have a 2008 Equinox with this problem so thanks for the answer. I don't overfill but will take it in to have it looked at. I always like to some sort of background help before heading to the garage!