My crew and myself were finishing up a car lot the other day and I shut my machine off to move the truck. Went to start back up and lost all pressure. I took the head off of the pump and checked the plungers and seals. All 3 plungers were moving free and the seals looked good. A local company suggested changing out the plastic back up rings which were worn. After that the pressure got better, but still not full pressure. I pulled off the unloader and it had quite a bit of grime in fresh water inlet so we ran fresh water through it to try to clean it out. It spit out a few more specks of dirt but it still wouldn't build full pressure. Could it be a bad unloader or do you think im looking at something in the pump? the pump oil is clean and not milky. Sorry for rambling, but im pretty frustrated with this. Thanks
HELP, Lost Pressure!!!
- Thread starter FTPW7
- Start date
N.A.P.W.O
New member
The unloader is a valve and if you already found dirt in it then it is probally the problem. Change it. Also you may want to check your vlaves themselves for debris. If you open the trigger on the gun, and all pressure is lost, but then when you let go the trigger and pressure builds in the lines, most likely debris in a valve. Again, the unloader is also a valve...
Pat Norman
New member
May have debris in the trigger gun too. Backflush it or disassemble and clean.
Yeah I pulled the valves out of the pump and cleaned them. They definitely needed it. Yes, NAPWO it is building pressure in the lines but losing it once the trigger is pulled. When I first pull the trigger pressure is full and after that it drops back down. Thanks for the input guys
I'm not hearing anything abnormal.. Is there a specific sound I should be listening for?
A little update here. Changed out unloaders and nothing changed. Pulled the head back off of the pump and checked the ceramic for cracks and such which was fine. Also pulled out the high pressure seals and checked those for damage which they turned out to be fine also. Im running off a 550 gal tank which is just gravity fed. Ive ran this setup on 4 different machines and it always worked out just fine. Not sure if I have a water flow issue or what though. But its running like its not getting enough water somehow. Its running at 2000 psi on the gauge, but as soon as you let off the gun it shoots up to 4000 on the gauge before the bypass kicks in.
Pat Norman
New member
It's this pump belt driven or direct drive? Most direct drives are not meant to be run tank fed. The pistons are too small.
Pat Norman
New member
Try to direct feed it off a hose with good flow and pressure and see if that fixes your problem.
Im seriously going to go nuts with this thing!! Bought a freakin $150 seal kit because I checked the oil this morning and it had water in it. Changed out the high and low pressure seals and still the same freaking thing. 2000psi and a small amount of pulsing action. Hooked directly into water source with good flow and still the same. Not sure where to go from here....
GrassButler
New member
May sound crazy........ but Hal mentioned running it without a gun ( ball valve closed )...... Did u try this? bad gun can cause the unloader and engine to go ape Sh_t!
Steven Rowlett
Member
Is it possible the engine speed is low? Have it checked with a tach. Check your throttle cable, sometimes they will work loose.
Last edited:
mike barrett
Member
Check your water filter, it may be clogged. Pull the hose feeding water to the pump head and make sure water gushes out. By pass the hose reel, run a hose from the unloader to gun and recheck. My guess would have been the unloader.
Thanks Mike. The filter had a little it of debris in it, but even after I cleaned it out it stil didn't fix it. The whole time trying to get this thing to run ive just been running a small hose from the unloader to the gun. Its the weirdest thing, when I run water from a spigot into the machine, with the hose unconnected it makes more pressure free flowing without the machine on than it does when I start the machine. As soon as I started it the water sprays all different directions with less pressure.
Ralph Q
New member
So you have you been using the same high pressure hose the whole time you are doing all this testing? Did you try another hose? You might have an obstruction in the hose somewhere causing the unloader to go into bypass. That would explain the water coming out normally with the hose unnattached.
Does the machine sound like there is a load on it when you attach the hose with no gun?
Also are you running a 4000 psi machine?
Does the machine sound like there is a load on it when you attach the hose with no gun?
Also are you running a 4000 psi machine?
Ive used a few different hoses during the testing. No, I doesn't sound any different than normal as far as I can tell, and yes, it 4.5gm 4000psi cold water unit. I may need to get a video up on here if I don't get it figured out here in the near future. Its about to drive me to drink.
Rance
Active member
I have the same problem with one of my units too. It's very strange. Pull the trigger, 2k psi. Let go of the trigger and BAM! 4k psi. Pull the trigger and psi drops back down to 2k.