New pump in power washer question

[threeputtpar]

So I just installed a new radial axial pump on a 5.5hp Honda powered pressure washer to replace the one that gave up the ghost, but upon first run I'm having problems.

Related facts: 5/8" garden hose with residential water pressure, no ball valves or quick connects to limit the volume of water the washer gets, the output hose and the nozzle are both clear, as are the filter screens on both ends of the pump.

I start the Honda with the water connected and running after I purge all of the air from the system, and it runs at full pressure for about 5 minutes. Then is will start to pulsate with high and low pressure and make the governor on the engine work. Eventually, it will lose high pressure and I then shut the engine off. Restart gets it back to high pressure for a little while, only to end up stalling the engine. No clunking noises from the pump, but I think I can hear it cavitate when it goes from high to lower pressure. If I stop the engine at that point and hold the wand handle, it purges out some air and then it will have high pressure again upon restart.

Did I just get a lousy pump and should I send it back to Amazon? Do I need to run some pump saver through it first to get all the internal seals and valve properly lubricated? There is enough oil inside of the pump body, so it's not the plunger binding.

Thanks for any help or tips you can provide.

 

[cat843]

The new pump has same spec (GPM and pressure) as old?

What brand of pump?

When the pressure goes low does the garden hose flatten as if there is a vacuum on it?

 

[Whimsey]

I didn't think that you are suppose to hold the pressure on high on a continual basis. You should briefly alternate the pressure from the wand. You might be stressing the pump if you're continually leaving it on high pressure.

Whimsey

 

[tmorris1]

Check for a plugged output nozzle.

 

[threeputtpar]

A quick follow-up. I hit the new pump with some B&S pump saver and lubricant that the BIL picked up with the new pump and while it was working its magic I hears something in the pump loosen up and click back to where it should be.

I'm assuming that there was a valve or two, or maybe the unloader valve, that was not playing nice and the lube freed it up. Currently my father is using said pressure washer to clean a garage at his rental.