Hot or cold engine, it will RANDOMLY turn over 5 to 6 times before starting; mileage 260k, over the past 2 months gas mileage has dropped from 33 MPG to 29 MPG's. The hard to start symptoms began 2 days ago. Car has a new battery; Batt terminal ends are not corroded; I run ONLY quality fuel; air filter in decent shape; I added a bottle of Chevron Techron prior to adding gas fill up Saturday evening and Tuesday morning, the car spins over few times before starting; there is no change in loss of acceleration or rough idling
A number of things can cause this but it sounds like the fuel pump check valve may be at fault. When you shut the car down, the check valve keeps pressure up in the fuel system. If it’s faulty or stuck, then when you shut the car down, fuel may be bleeding back to the tank via the return line.
The next time you start the car, turn the key to the ON position and wait a moment. You should hear the fuel pump priming the system but it should only run for a moment or two. Try turning the key off and on a couple of times prior to starting the car. If it starts right up after doing that, the check valve is at fault. Most will require replacing the fuel pump as it is internal. If you need help having this checked, a professional from YourMechanic can come to your car’s location to diagnose the hard start and let verify what should be done.