What should be checked for troubleshooting failure to prime?

When troubleshooting a failure to prime in a mobile pump setup, maintaining the engine's RPM and ensuring that all couplings are tightly secured is crucial. A pump relies on proper rpm to create the necessary vacuum for water to be drawn into the system. If the engine's RPM is too low, it may not generate enough suction, which can prevent the pump from priming effectively. In addition, loose couplings can allow air to enter the system, further impeding the priming process. Ensuring both elements are correct fosters an ideal operational environment for the pump to function properly.

While other options may seem relevant, they focus on aspects that do not directly influence the priming process. Cleaning the water tank (potentially beneficial for maintenance) or replacing the priming device (an action that may be necessary if the device is faulty) do not address the immediate need to establish a vacuum for priming. Checking whether the engine is overheated is also pertinent for overall performance but is not specifically linked to the initial challenge of failing to prime.