voltage too low at dc motor
You are not providing consistent information about your problem, but you really don't need to.

Your transistor is not being driven hard enough to turn on fully.

Your pump, from its voltage and current ratings, needs about 0.25 to 0.33 amps. This is at the upper limit of what a 2N2222 can handle. See,the data sheet and look at the Collector/Emitter Saturation voltage. A properly-driven 2N2222 will drop about 0.4 volts at 150 mA, and 1.6 volts at 500 mA, so you should expect a best-case voltage drop of a volt or so.

And what constitutes a properly-driven transistor? Base current one tenth the collector current - in your case, about 25 to 30 mA. Now look at the R3 specs and you'll see a maximum of 20 mA output current for an IO line. However, this 20 mA is probably not available to your circuit. Try measuring your D9 output, and I'd guess it will be in the vicinity of 3 volts or a bit more. Let's say 4 volts. The base current will then be $$i_b = \frac{V_{D9}-0.7}{0.220} =  \frac{4-0.7}{0.22} = 15\text{ mA}$$ which is only half of what you need. So the 2N2222 is not being driven hard enough and is dropping more voltage than you expect. It's also getting pretty hot.

So, you need a better output stage. Either use another transistor to increase overall gain, or go to a MOSFET. If the latter, make sure you use a logic-level FET. Regular MOSFETs will usually have a gate threshold which can be high enough to cause similar problems to what you're seeing.