We bought a new (used) car a couple of weeks ago and it was running fine up until Sunday. Since then it still runs fine except the startup from cold.
Last week it was fine, starting up within a second or so of turning the ignition. Since Sunday however it takes a couple of seconds for all the cylinders to fire. The first couple still start up almost instantly but then it sounds like it takes a few rotations for the other cylinders to start. After that it runs fine, and restarting the engine straight after all cylinders are firing gets it starting instantly.
One thing I wonder is whether it is fuel related. We let the tank drain almost completely (5l left) and refilled it on Saturday which leads me to wonder if it may be a contaminated fuel issue (or even some kind of gunk from the tank)? Other things I'm wondering is whether it may be a starter motor issue (battery voltage is fine), or even not turning the key long enough, but the latter would be odd as there are two of us driving and it's started happening to both of us at the same time.
The vehicle is a 2010 Ford F150 5.4l V8 - yes I know it's unlikely anyone has any specific knowledge with the engine but I it doesn't seem like it's an issue specific to that engine. And besides, all the F150 forums are full of rednecks and scare me.
Last week it was fine, starting up within a second or so of turning the ignition. Since Sunday however it takes a couple of seconds for all the cylinders to fire. The first couple still start up almost instantly but then it sounds like it takes a few rotations for the other cylinders to start. After that it runs fine, and restarting the engine straight after all cylinders are firing gets it starting instantly.
One thing I wonder is whether it is fuel related. We let the tank drain almost completely (5l left) and refilled it on Saturday which leads me to wonder if it may be a contaminated fuel issue (or even some kind of gunk from the tank)? Other things I'm wondering is whether it may be a starter motor issue (battery voltage is fine), or even not turning the key long enough, but the latter would be odd as there are two of us driving and it's started happening to both of us at the same time.

The vehicle is a 2010 Ford F150 5.4l V8 - yes I know it's unlikely anyone has any specific knowledge with the engine but I it doesn't seem like it's an issue specific to that engine. And besides, all the F150 forums are full of rednecks and scare me.
