When you tap on the starter, what you are actually tapping on is the starter solenoid; a device mounted on the starter (on most cars) that engages the starter gear to the engine gear while simultaneously connecting battery power to the starter. When the start solenoid gets to the point where you have to tap it, the remaining life is difficult to predict because it really depends on what's going on inside the solenoid (e.g. how many start cycles it has completed, exposure to elements etc.). However, the good news is you can normally go to an electric motor repair shop and buy a new solenoid for much cheaper than the whole starter, and in many cases, much easier to replace.
Probably a bad starter solenoid.
wrong key when using the remote starter the starter does't crank long enough to start the car. Starting the car with the key the car starts five. Could use some help.
There could be a bad sylanoid or a bad starter...
Starter is defective, or battery is weak.
Starter motor problems, charging system problems, wiring and connection problems between battery, alternator and starter. To many possiblities to list. If the battery is still charged and you need to jump the car to get it to start you have a bad starter. Now you say how can that be? it starts when its jumped? Correct the starter is drawing too much power"amps" and having a second battery "the jump" appx doubles the amount of amps to the starter allowing it to start. Replace the starter and problem will go away. Besides it wont take too long before a jump wont allow it to start.
The starter or battery could be weak. The weakness will cause the starter to turn too slowly to start the truck.
Could be your starter.
lack of fuel
probably the starter at least that is where I would start at anyway. I had the same problem but after so long the car would crank and I was told the starter but have not had problem again.
2004 mercedes truck wont start sometimes. Why
Defective starter bendix.
Starter may have gotten wet and frozen or shorted. Check wiring to starter See if you are getting power to starter