Pump Problem?

T

tommy

Member
I have a 4 gpm @ 3500 psi. pw. I reduced the pressure using a 25055 nozzle to around 2000-2500 psi. When I let go of the trigger the pressure will rise to 4000 and then drop to 3000 in about 4 seconds then it goes to 4000 again. Is this normal?

I have a hotbox that is rated to 3000 psi and was wondering if this extra pressure when in bypass would hurt the box. The pressure guage is located near the input of the hose reel.


Tommy
 
Tommy,
It sounds like your sucking air while in bypass. Do you have any leaks? They will make the unloader cycle. Fix them and your problem should go away. May be an o-ring, gun leaking, leaking fitting ect.

Usually you don't want more than a 10% -350 psi swing while in bypass.

Hopefully you didnt try adjust the pressure down using the unloader. If you did you will need to reset it using one of your standard hp nozzles.

While your in bypass you have no flow to the hot box. Your burner should shut off until flow resumes.


A 5.5 nozzle = 2,000 psi 3.80 gpm
A 5.0 nozzle = 2,500 psi 4.0 gpm

Hope this helps!
 
I have seen this problem many times over the years and the bypass is not the answer the tip is too big. A #4 would work best.
 
I put a 4.5 nozzle and the pressure went up to around 3500psi, but when I turn off the trigger the pump will go to 4100 psi then down to 3000 then back up again.

I will try to find if any leaks are present.

Won't a 4.0 nozzle up the pressure? I want to keep the pressure under 3000 as to not damage the hot box.

Tommy
 
Yes but then you adjust the unloader down. This will stop your spike problem
 
Back the nut on the unloader down!
 
Tommy,
Do you have a pressure or flow type unloader?

When you squeeze the gun on the pressure type, pressure comes up immediately and the gun kicks back.

The reason I ask is the adjustment procedures are opposite of each other!

Also before you adjust either type you must first loosen the lock nut!
 
Last edited:
The smaller tip will lower your gpm output and reduce your spike deadband.

Adjust the unloader down to get lower pressure without the high spike.
 
Tommy,
Give Wiz a call I am sure he can walk you through your problem.

He is a tremendous resource.

For educational purposes you can go to FAQS at www.generalpump.com

They have trouble shooting and other info on their sight.

Does not matter if you don't have a General pump. The info is generic
 
Last edited:
Got her fix. The problem was a leaking O ring in the hose reel. After getting this fixed the unloader does'nt cycle anymore.

Thanks for everyones help.

Tommy
 
You must log in or register to reply here.
Back
Top