My son has a 2009 cobalt he drives long distances to work. It developed problems in that it is hard to start after refueling every time. Once it starts and the car is driven for a while, it will start regularly when cranked. I have changed the fuel filter, but the problem
Continues. Any suggestions or ideas?
quoted to make it easier to read.
What exactly is the car doing during this “hard start”? Crank, but no fire? No crank?
When refueling, does your son fill the tank full everytime? Possibly to the point of overfilling? Any idea what happens if he only fuels to about half tank?
The car just turns over without cranking. The way he described it it sounds like the car is Vapor locking. He drives The car hundreds of miles to the job site so yes he fills it up every time. After he lets the car sit for a little bit at the station the car will start.
is the check engine light on?
How long to sit before it will start?
For giggles, next time he needs to get fuel, have him fill up about half way, button everything up and start it and see if it does any better. He doesn’t have to leave the station, just try it and see what it does. He can finish refueling after he tries it. Might waste a bit of time, but might provide some valuable insight, too.
I’d also admonish him to not top off, if that is a practice that he currently does. Once the pump clicks off, don’t add anymore fuel.
Here’s the On-board Refueling Vapor Recovery system.
What might be happening is the EVAP Vent Solenoid Valve is stuck open and fuel vapors are being forced into the engine causing a flooded condition.
To find out if this what’s happening, the next time your son fuels up have him hold the gas pedal all the way down to the floor. If the engine starts that’s probably what’s happening.
Don’t admonish your son if he tops off the gas tank. On an OBDII vehicle, you can’t overfill the gas tank. There’s an overfill check valve in the system that doesn’t allow that. This valve also acts as a roll-over check valve.
Tester
Thanks for the insight guys. I will discuss this with him when he gets back in town. And yes, the light is on, but that was on before due to the previous owner modifying the air intake with an aftermarket racing style air intake. Not sure how long he lets it sit before it cranks, can’t seem to get a clear answer out of him about it.
The purge valve is stuck open, when the tank is being filled the intake manifold and air cleaner are being filled with gasoline fumes causing a “flooded” condition.
Have your son get his DTC codes read. There may be more than just the one you know about.
This could help.
As for overfilling: not a good idea
https://www.louettaautomotive.com/why-you-shouldnt-top-off-your-gas-tank/
It provides a method of controlled escape for gasoline vapors during the refueling process. It has a mechanism which closes the vent in the event the vehicle rolls over, to prevent spilling of VOCs or fuel in general. It also acts as a fill limiter.
Tester
He has told me he has to pump the pedal numerous times to get it to start and the. Shift it into to gear and take off quickly or it will sputter and quit after he fills it up. Sometimes he does over fill it, sometimes not. Once it starts it runs fine after that until the next fill up.