Pump Pulsating during Bypass

[LSP]

my pump is pulsating during bypass before the trigger on the gun is activated

once the trigger is activated it does not pulse

or if i adjust the unloader all the way down in pressure to about 500psi then it stops pulsing during bypass

any ideas for me ?

 

[cbchevy4x4]

Most likely the Unloader is on its way out, swap with another bay or put a new one in to see if problem moves with the unloader to whatever bay you put it on or goes away with replacing. could also be a water supply restriction to the pump.

 

[Randy]

I'd start by replacing or swapping the Regulator/Unloader with another known good bay and go from there. If it does after you swap or replace the regulator/Unloader then you've got a head problem.

 

[LSP]

With a new unloaded it is still pulsating during bypass but not as bad as before the unloader change

would it be the pump even if once the trigger is depressed it doesn’t pulse ?

 

[cbchevy4x4]

if its not as bad but still doing it, id venture to guess a seal or valve o-ring is on the verge of letting go in the head. A new unloader will help "hide" the problem but the problem is still there. Ive been know to use a screwdriver as a stethoscope to listen to each port and sometimes been able to narrow it down pretty quickly without tearing stuff apart.