always takes a few attempts to start the engine (no cranks), even with new battery

Question

it always took me a few attempts to start my sienna 2000 (130k mi). so I have battery replaced (it was about 12.3v). it went well the same day. the next day I failed to start it again (again, no cranks, took another few attempts to get it started). thought it was parasitics drain, so after one successful use of the car, I disconnected the battery, so its voltage is kept around 12.6v. the next day, still took a few attempts to get it started. no cranks. so my question is: something wrong with the starter? what part of the starter? it is hard to start, and potentially leaking (since I have battery disconnect during the night, parasitics drain issue can be excluded. I've also measure resistance along the path (from battery + terminal to starter solenoid, the resistance is almost negligible))

Update: here is what I do these days: disconnect the battery at evening to prevent overnight drain. connect in the morning. try 2~3 minutes to start the car (no cranks), it will eventually start, and voltage is ~14v when car is running.

Answer 1

Starting problem could occur due to various reasons:

1. Battery issues:Since you have already replaced the battery so this could not be an issue here.
2. Old spark plugs/improper gap:Adjust the spark plugs for the proper gap as per the manufacturer's recommendation. Replace if necessary

3. Impurities in fuel line:It could be possible that your fuel would have been contaminated due to some impurities.Chances are rare but it could be possible if you had a car sitting idle for a long time the fuel tank would have corroded.

4. Starter motor brushes:Again if you have a very old car the carbon brushes of the starter motor would have worn out which makes contact with the rotor of the motor. You can replace the carbon brushes(cheap but challenging) or replace the motor itself.

Answer 2

Important Question

Does the car produce any clicking sounds when you turn the key?

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Just to add a little more, the starts can lose function for a couple other reasons as well. In my experience grounding loss has been the most frequent cause for start failure.

From here I see 4 steps to try:

1. Thoroughly clean your primary grounding point. This will come off the "-" terminal on the battery and tap into the body somewhere (generally nearby). Disconnect it and clean the terminal and mount surface with sandpaper (150 grit works nicely). Wipe the surfaces of debris and reattach. Then see how it works.
2. Take the starter off and take it to a shop to be tested. (Note: A shop's bench test is not 100% accurate since the starter is not under load. Bad brushes can pass the bench test but fail real-world.)
3. With the starter off, clean both mating surfaces. (I haven done it, but you can also use dialectic grease to help things.) then reinstall the starter and see if that works.
4. Finally, replace your starter altogether. As mentioned, you can rebuild parts of the starter, but if you're not savvy, you can end up messing it up more.