If your water pump pulses frequently it's quite likely it has a leak or is drawing air into the system? One of the most common water pumps fitted in motorhomes is the Shurflo Trail King 7. Although spare parts are available, a complete new pump costs little more than the parts.
A short video showing how easy it is to replace the pump and also the inlet filter.
It's fairly a straightforward job. 
And then Add to Home Screen.
