My car is Camry 2004. It runs well, but the problem is hard to start after sitting for few hours or longer. It took three to four times to have the engine start with gear pushing. i have changed the idle system, fuel pump, fuel injector, battery, fuel sensor, cold start sensor, ignition coil, and spark plug. But It does not get well, the problem is still unsolved.
After changing the spark plugs, the engine starting well for three days and then get back to the same situation.
When the trouble is occurring try spraying a small amount of starter fluid into the air intake to see if the engine fires up then. If it does then it would seem there is a fuel problem causing the issue. If that doesn’t help then check to see if the plugs are firing.
Another possibility is the check valve in the fuel pump is allowing fuel to leak back into the tank. To see if that is the case prime the fuel line by just turning the ignition ON and Off several times before going to the START mode.
When you changed the fuel pump did you change the fuel filter? If it has an external filter and it’s too dirty, it will restrict fuel flow. If you turn the key on and off three or so times it would point to a dirty fuel filter or a check valve in the pump as mentioned above. The pump was just just changed, so I’d look to the filter.
The next time you go to start the engine after it has sat, turn the ignition switch on for two seconds so the dash light turn on, and then turn the ignition switch off.
Repeat this a half dozen times and then try starting the engine.
If the engine starts, you got a fuel pump with a bad anti drain-back valve.
Another idea, gasoline is leaking into the engine as the car sits after running, possibly by way of a defective injector(s). When you changed the spark plugs that may have allowed some of the gasoline in the cylinder(s) to evaporate when the plugs were out, which would explain why it started ok then. A fuel rail pressure hold test would confirm.
To test this theory, when it won’t start, you could remove all the plugs, crank the engine a few times, then put the plugs back in. If it starts right up then, good chance that’s the problem.
It’s a lot easier to turn the key to run, push and hold the throttle to the floor and crank until it starts, then let off the throttle.
On fuel injected cars
Pushing and holding the throttle to the floor puts the computer and injectors into flooded start mode and limits or shuts off the fuel being injected depending on the car.
Then the next most likely thing is leaking injectors as @George_San_Jose1 suggested. Proper use of a fuel pressure gage can tell you if it’s injectors or pump. Another possibility is a very small leak in the fuel lines not noticable because of evaporation.
I have tested the pressure of fuel pump, it’s in good condition. Car service cannot solve this
problem and i am preparing to buy a new one. Thanks for good recommendation.