Unloader - over pressure, no flow

tomtucson

tomtucson

New member
I have the green spring unloader, run 9-10 gpm, bypass to tank. I turned the machine on and the pressure gauge on the head goes to 4500 psi, gun closed!? Turned it off and it didn't happen again. This happened before a long time ago when I let off the gun the pressure would shoot up instead of down. ??
 
tomtucson said:
I have the green spring unloader, run 9-10 gpm, bypass to tank. I turned the machine on and the pressure gauge on the head goes to 4500 psi, gun closed!? Turned it off and it didn't happen again. This happened before a long time ago when I let off the gun the pressure would shoot up instead of down. ??
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Sounds like the unloader is getting stuck till the pressure opens it up???
 
Sticking Unloader

Take off the nut on top of the spring. Spin the sping nut unitl it is loose take it off. You will have a rod left. Take a wrench and remove the nut that the rod protrudes through. Pay attention to the washer and ball as you take them out. Look over the oring and lube up the rod. Check the ball and see if it has flat places. If so change the ball. If not put it all back together. It should work after you oil it. The slide on the rod can get corrision and bind up. You should be able to fix this in about 1/2 Hour. This is not something you want to ignore.
 
Tomdurbin said:
Take off the nut on top of the spring. Spin the sping nut unitl it is loose take it off. You will have a rod left. Take a wrench and remove the nut that the rod protrudes through. Pay attention to the washer and ball as you take them out. Look over the oring and lube up the rod. Check the ball and see if it has flat places. If so change the ball. If not put it all back together. It should work after you oil it. The slide on the rod can get corrision and bind up. You should be able to fix this in about 1/2 Hour. This is not something you want to ignore.
Click to expand...

I bought the 8GPM machine I mentioned in another post and it has the same problem. When I let the gun off it raises the pressure to 4000PSI. When I turn the gun on with 8 size tip wand connected directly on the whip hose, it gives me 2700-2800PSI when it is supposed to be 3500PSI. Should I just replace the unloader with better one or try to fix it (if that's the issue)? I'll take it back to the shop and have it checked out.
 
FoxSweeping said:
I bought the 8GPM machine I mentioned in another post and it has the same problem. When I let the gun off it raises the pressure to 4000PSI. When I turn the gun on with 8 size tip wand connected directly on the whip hose, it gives me 2700-2800PSI when it is supposed to be 3500PSI. Should I just replace the unloader with better one or try to fix it (if that's the issue)? I'll take it back to the shop and have it checked out.
Click to expand...
What you are experiencing is pressure spike. Thats is what the unloader builds to until it opens and goes into bypass. This is why you should never adjust a pressure trapping unloader without a gauge mounted between the gun and wand. This what I would do first. Take the hose loose that is connected from the top of the pump to the unloader. Connect your whip hose to this hose. Take the bypass line off of the unloader. Make sure you have your gauge connected. You might want a little help just someone to start the pressure washer. Pull the trigger on the wand (make sure you have the proper tip) Have someone start the machine. Check the pressure. My guess about 2400psi. If that is the case that is all you will ever get out of that pump. Reinstall the unloader and adjust it down until the pressure spike is only 7% (some say 10%) of the pressure you are getting off of the head. If this is 120v unit I would check my voltage under load and idle. Before you do any of this. They might just crank up the rpm to give you more pressure when you take it back. If your generator is putting out less than 105 or more than 130 underload you will be lucky to get three years out of the generator. The other thing is without enough power the burner will soot up and you will be pulling the coil washing it and reinstalling it every six months.

REMEMBER THE UNLOADER JUST REGULATES THE PRESSURE IT DOES NOT MAKE PRESSURE. YOU CAN CRANK IT IN AND GET ARTIFICIAL PRESSURE. BUT IF YOU DO THERE WILL BE CONSEQUENCES.
 
Tomdurbin said:
What you are experiencing is pressure spike. Thats is what the unloader builds to until it opens and goes into bypass. This is why you should never adjust a pressure trapping unloader without a gauge mounted between the gun and wand. This what I would do first. Take the hose loose that is connected from the top of the pump to the unloader. Connect your whip hose to this hose. Take the bypass line off of the unloader. Make sure you have your gauge connected. You might want a little help just someone to start the pressure washer. Pull the trigger on the wand (make sure you have the proper tip) Have someone start the machine. Check the pressure. My guess about 2400psi. If that is the case that is all you will ever get out of that pump. Reinstall the unloader and adjust it down until the pressure spike is only 7% (some say 10%) of the pressure you are getting off of the head. If this is 120v unit I would check my voltage under load and idle. Before you do any of this. They might just crank up the rpm to give you more pressure when you take it back. If your generator is putting out less than 105 or more than 130 underload you will be lucky to get three years out of the generator. The other thing is without enough power the burner will soot up and you will be pulling the coil washing it and reinstalling it every six months.

REMEMBER THE UNLOADER JUST REGULATES THE PRESSURE IT DOES NOT MAKE PRESSURE. YOU CAN CRANK IT IN AND GET ARTIFICIAL PRESSURE. BUT IF YOU DO THERE WILL BE CONSEQUENCES.[/QUOTE]


Right on Tom.
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Thanks very much. What I'm curious about, just to know whats going on, is the gauge on the head reads zero when you stop spraying - 3000+ in the hose, but zero at the head. when this happens and its reading a continuous ~4500, where is the water going? It seems like its pumping. I feel connected with my equipment and this makes me feel bad.
 
I'm going to address this to Tom, I kind of have a poll going - Doesn't that 3 mm hole inside a k-7 cause a lot of restriction and work for the pump to squeeze it through there?
 
tomtucson said:
Thanks very much. What I'm curious about, just to know whats going on, is the gauge on the head reads zero when you stop spraying - 3000+ in the hose, but zero at the head. when this happens and its reading a continuous ~4500, where is the water going? It seems like its pumping. I feel connected with my equipment and this makes me feel bad.
Click to expand...

Take the outlet fitting off the unloader. Inside is a brass piston (which should have an o ring on it) and a spring. Make sure the piston moves freely and the o ring is intact.
 
the head will read 0 pressure because when the unit is in bypass there is no load on it pump just after the unloader.

If you have K7 it should not be trapping any pressure before or after the unloader if it is you have some junk in it.
 
Got that Paul, what I was curious about is when this happened (pressure trap - green spring) the gun is closed and the head is reading like 4500!
 
Unless it is just killing you to know what your pressure is, I would throw your gauge away. I have never owned one or cared what my pressure is, especially when setting my unloader. I want the volume. I adjust until there is no water coming out of the bypass when the trigger is pulled. That's just me though, and I have been called hard headed:eek:
 
I think I'll take it apart to see how it works but replace it anyways, its got enough hours on it. Good stuff to know, I didn't know there was any maintenance you could do.
 
The reason why the head reads pressure is your unloader is not going into bypass. Try cleaning as desribed. Put a moisture resistant oil on the slide check it for rust. Sooner or later its gonna stick and stay stuck. Then Kabooom. New pump.
 
Tomdurbin said:
What you are experiencing is pressure spike. Thats is what the unloader builds to until it opens and goes into bypass. This is why you should never adjust a pressure trapping unloader without a gauge mounted between the gun and wand. This what I would do first. Take the hose loose that is connected from the top of the pump to the unloader. Connect your whip hose to this hose. Take the bypass line off of the unloader. Make sure you have your gauge connected. You might want a little help just someone to start the pressure washer. Pull the trigger on the wand (make sure you have the proper tip) Have someone start the machine. Check the pressure. My guess about 2400psi. If that is the case that is all you will ever get out of that pump. Reinstall the unloader and adjust it down until the pressure spike is only 7% (some say 10%) of the pressure you are getting off of the head. If this is 120v unit I would check my voltage under load and idle. Before you do any of this. They might just crank up the rpm to give you more pressure when you take it back. If your generator is putting out less than 105 or more than 130 underload you will be lucky to get three years out of the generator. The other thing is without enough power the burner will soot up and you will be pulling the coil washing it and reinstalling it every six months.

REMEMBER THE UNLOADER JUST REGULATES THE PRESSURE IT DOES NOT MAKE PRESSURE. YOU CAN CRANK IT IN AND GET ARTIFICIAL PRESSURE. BUT IF YOU DO THERE WILL BE CONSEQUENCES.
Click to expand...

I just got a new VB80/280 (blue spring) unloader. When I adjust it, how can I measure the pressure spike to be 7-10%? Just to make sure I understand it right, the pressure spike is the little flow of water through the bypass line when the gun is open and under pressure, right?

The new one has additional 1/4 whole. The old unloader doesn't have it. Is it for gauge hook up or something else?
I kind of dont understand the above guide. "This is why you should never adjust a pressure trapping unloader without a gauge mounted between the gun and wand." When adjusting the unloader, shouldn't I have the gauge on one of the unloader's outlets and just a whip hose from the unloader to the gun with the proper nozzle?

Thanks!
 
I was loosing pressure and it turned out to be that my engine was rinning a lil slow. as soon as they adjusted it it was back to 3k before 200' of hose dont forget about the pressure loss at the end of every 100' of hose. also (fox) check the pump head pressure before the coil and after it should be about the same. if its lower after the coil you have a clog in the coil. If im not mistaken.please correct me if im wrong.
 
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