Low Output Pressure

[Roger]

Anyone have any ideas on the correct way to adjust and or test an unloader?

Here are the symptoms. My unit is a Tuff 5gpm @ 3k psi (admiral pump 1750rpm 4.9gpm @3000psi) not sure what type of unloader it is, there is some lettering on the back side of the unloader but cant see it because fittings and battery are in the way. I attached a pic below, maybe someone can identify it. Open gun with a new 5.5 tip the pressure at the burner output is about 2200-2300 psi max, the closed gun pressure at that point is about 4200 psi. Typically what should the pressure differential be between an open and clossed gun? Adjusting the the unloader will lower the pressure but can't get above 2300 psi. Adjustments were done in the following maner, open the gun, adjust the knob and note the pressure, close the gun and again note the pressure. Is that the correct way to make adjustments?

Could the open gun pressure be low because it's staying in bypass? Is there there a way to test that other than pulling the bypass hose off and seeing how much water is comming out while the gun is open?

Am I looking in the right area to find the problem, or am I barking up the wrong tree? What else might be causing the low pressure problem.

If this is a unloader problem, is this type of unloader rebuildable or is it better to just replace it.

Thanks in advance, any help would be appreciated.

 

[Roger]

Let's try the pic again....

 

[washmasters]

I just went through all of this a couple of weeks ago, but my unloader was flow actuated and I tried to switch to a pressure actuated because I wanted to be able to adjust the pressure. If the unloader was stuck in bypass you wouldn't be getting pressure. The difference in open and closed guns is called the spike pressure and there should only be about 300 to 400 psi difference. So if you are running at 2300 the unloader should spike at about 2700 and then kick into bypass. You do pull the trigger to adjust the thing and see how far it spikes before it kicks into bypass. If it is over the 400 range then you have to adjust the pressure back down. I don't think that it is the unloader but I could be wrong. There isn't much to those things. I would check my filters and make sure there wasn't any drips or sucking air anywhere. The thing isn't running choppy is it? Just my opinion. Another opinion: If you do ever buy another unloader, buy a flow actuated one. Much smoother and easier to operate. I tried the pressure actuated and it doesn't compare.


Lance


Lance

 

[Steven Rowlet]

Roger, Take a look at your check valves. If they are worn water could be flowing through and not allowing the pump to build full pressure. Washmasters gave you the right information about spike levels. It is still possible the unloader is at fault. It is always a good idea to keep an extra unloader on hand.

 

[Mark]

Roger,

The unloader appears to be an AL606, (one of my favorites)
it is rated for 8 GPM @ 3600 PSI. I would pinch the bypass line closed
while running unit with trigger pulled, if the pressure increases, as I
think it will, the unloader is bypassing water. this unloader is rebuildable,
however we sell this unit online for $39.95
(Hardly worth rebuilding at that price)

AL606 Unloader

I asume there is no leaks from the pump, and it is running smooth with
no noticeable pulastion? If so I would bet the unloader is the culprit.
The "Spike Pressure" should be @ 10% over operating pressure.
(3300 to 3450)

 

[Roger]

Lance,

Thanks for the input. I didn't think the spike pressure should be as great as I am seeing. I have redone all the fittings on the input side of the pump even installed a new screen. No leaks anywhere.

Mark, Thanks for the suggestion of pinching bypass hose with the gun open. That is so simple don't know why I didn't think of that. I'll give that a try tomorrow. I did dig around on your site today and found it was an AL606. Also saw a repair kit was available. Didn't know what it cost or if it was worth the effort to rebuild it.

Thanks again,

 

[B.E YOUNG Sr]

Roger,
When my unloader stuck in bypass I didnt have any pressure at all! If you want to rule out the unloader remove it. Connect your quick couple directly to the pump head output. With the GUN OPEN start the machine. If your pump is functioning correctly you should reach full pressure. Remember ONLY TRY WITH GUN OPEN!
If you have an easy start valve check it also. Disconnect the ouput hose from it. When you preform the above test, upon first starting it should pass water. Once the pump comes up to pressure the valve should close and have no output! If it still passes water it needs to be replaced.
Have you checked your new nozzle and varified it is labeled correctly?
Is the pump oil milky white in color or normal?
Is the pump head leaking a little?

Hope this helps! Been there. Got a lot of good info from the guys on this board! Purchase the book THE UNIVERSAL GUIDE TO HIGH PRESSURE AND STEAM CLEANER REPAIR.
Even if you dont do your own repairs it will give you enough insight to keep from getting hosed.

Another big thing. buy spare parts we dont make any money sitting at home.


Stay dry!

 

[Bill B]

You may want to confirm your tip is ok. Try another tip and see what pressure runs.
Also, I don't have my pressure-gpm-nozzle tip sheet close by, but I use a 5.0 tip on a 4000 psi / 5 pgm machine. You should probably be using a smaller tip. The larger orifice on the 5.5 will lower pressure more than you would guess.
B2

 

[Roger]

Bill,
Thanks for the suggestion. My first thought was that I might have a mislabled tip, so I tried severl tips all new, same pressure with each. The chart I have(the one printed in Delco's newsletter) calls for a 5.5 tip, 4.8gpm @3000psi.

Mark,
I think I may have found the problem. I tried your suggestion and the unloader doesn't appear to be bypassing any water with the gun open. My previous pressure mesurements were taken at the output of the burner coil, so I installed a guage in the input side of the burner coil and checked the pressure. The coil seems to be the problem. I was able to adjust the unloader (measuring at the coil input) to 3000psi with a spike pressure around 3400psi but there is an 800psi pressure drop across the coil. Must be really clogged up with crud. Now I need to look thru past posts to get info on descalling my coil.

Thanks everyone for your help,

 

[Glenn]

No one mentioned this but whenever you have a drop in pressure, one thing I always check is pump and engine rpm. This will effect both the gpm and pressure output.
Glenn

 

[Roger]

Update on the low pressure.........

Bought some ScaleAway today, mixed it as per the directions and circulated it thru the coil for about 40 min. You wouldn't beleive the crud that came out, it was black and washing out chunks of crud. Flushed it with clean water till it ran clean then hooked the hoses back up and cranked up the unit with a open hose, black water and chunks came out for 2-3 min. Put the gun on with the correct tip, the pressure was up to about 2500psi. Fired up the burner and the temp climbed faster than before. Even more crud came out. Circulated the ScaleAway for another 30 min, even more crud came out. After flushing it again and firing it up, the pressure is up to 2750psi with a spike of about 3500psi and the water heats up a lot quicker. Still about 200 psi drop across the coil, might need a littlt more cleaning still, but will run it like that for a while and see how it does.

Thanks for everyones help,

 

[Steven Rowlet]

Roger, It's a good habit to clean the coils once or twice a year. I usually do it twice a year. The hardness of the water has a lot to do with it. Glad to know you found the problem. The coils being clogged like yhat will also keep a down stream chemical injector from working by not allowing enough drop in pressure.