If your airless spray pump primes and pressurises but nothing happens when the trigger is pulled, and it is not the airless spray tip that is blocked, the actual spray gun hand piece could be where the problem is located.
The first thing that needs to be done is relieve all pressure from the airless spray system by opening the prime spray or bypass valve and turn the machine off.
Serious injury can occur if an airless spray unit is not used correctly.
Even small handheld DIY airless spray guns reach pressures which can cause serious fluid injection injury. Never place any part of the body near nozzles or remove guards.
Always ensure that all components of your airless spray machine including airless paint spray hose, spray gun and airless spray tip are rated to a working pressure that exceeds the output of your airless spray pump.
Diagnosing problems with valves in hydraulic diaphragm airless paint sprayers.
Hydraulic diaphragm airless paint spray machines are usually fairly basic simple machines with not much to go wrong. Unlike piston airless paint sprayers the valve action in diaphragm airless sprayers is much more passive and susceptible to problems that may not ordinarily affect piston pump.
A piston airless paint spray may effectively continue to operate using only one of the two valves commonly found in piston airless paint sprayers and enable the operator to complete a job.
A most common cause of airless spray gun problems and early failure are a result of incorrect cleaning and airless paint sprayer storage procedures.
When your airless paint spray job has completed the first step is to recover as much of the remaining paint that still remains in the airless spray unit. Consult your airless paint sprayer operation manual for the recommended procedure to remove any remaining paint from the airless machine and to properly flush the airless unit out.