Looses pressure to spray when you pump it up.What do I do

fix the leak as the pump build pressure switches off , the leak looses pressure pump switches on and so on
fix the leak and the pump will build pressure and switch off until the tap is used

It sounds to me that there is air in the pump, remove the nozzle if possible and pull trigger until the air works thru the pump.

You can take the intake part of the pump apart and clean/lube the diaphragm of the pump. If you didn't clean it out last time it was used there will be residual or cake built up. Make sure the down snorkel is clear and doesn't have any contamination in the tube. Check the screen/filter also.

check fuel pressure regulator or have pressure check done on fuel pump

Sounds as though the fuel pump is worn out.

Clean the tube too.Also make sure there is no debris in the bottom of the caister.

In some cases worn cam bearings can cause it. Not saying I know that applies to your vehicles engine. Just an unpleasant thought I had.

Fuel Pump RELAY & FUSE CHECKED & DO you Have POWER "TO" Fuel Pump ? ALSO OIL Sending Unit Supplys the GROUND To Fuel Pump , This is A Saftey FEATURE that Shuts Down Fuel If ENGINE Looses OIL PRESSURE . And If This OIL Sending Unit or also Called (OIL PRESSURE SENSOR) << If It FAILS it WILL Cause What Seems Like A Fue Pump Problem But Is Rally Just The Sensor that is BAD. HOPE this Sheds Light on Your Problem !

fuel pump possibly?

most likelly when your fuel pump gets hot it looses the pressure going to engine replace fuel filter and if this dont help then have the fuel pressure test done when problem is present
and if not good replace fuel pump