Loss of Pressure?

[Klean Spray 14]

I have a Honda twin V 24hp@4000-psi 5.5gal machine. Lately I have noticed when the trigger is relased after about 10-seconds the machine will go out of by-pass and spike up to the normal 4300 psi and fall back down to around 2500 psi all with out the trigger being pulled. . This repeats as the machine goes in and out of the by-pass mode about every 10-seconds with out the trigger being squezed. If I pull the trigger to start again the pressure drops down to around 2200 psi with a 25-degree tip and SLOWLY rises to almost 2800- 2900 psi max. is all I can get. I have checked hose fittings, jumper hoses etc. and can find no leaks that are visable.

Question: Could this be the unloader gone bad?

Thanks for any thoughts.

[mick m 19]

Yep, unloader. If you have it plumbed in to your tank, pull out the bypass hose with the trigger depressed....there should be no water coming from the by pass hose.

[Klean Spray 14]

Thanks Tricky!

I think I stand corrected. I did check for water leaks on all pressure washer hose fittings and connections BUT did not think about the small leak at the "inlet" side at the water supply tank bulk head fitting (45-degree PVC fitting). After looking, it actually had a crack at the 45-degree and was leaking water. I'm guessing after I re-plum I should be good to go?

[Douglas Hicks 128]

Thanks Tricky!

I'm guessing after I re-plum I should be good to go?

Try galvanized fittings when you do the repair. They seem to hold up better. If you use unions, a bit of anti-seize on the faces helps when it is time to take the union apart.

[Klean Spray 14]

Still having the same problem. I repaired with galvanized fitings and new 3/4 ID hose. Whith the trigger depressed and in by-pass their is water POURING back into the float tank like it should but the machine is still doing the orginal slow loss of pressure and in and out of by pass?

Could it still be the Un-Loader?

[mick m 19]

Its your unloader. Start your machine, squeeze the trigger & at the same time pull out your return hose to the tank, out. Their musn't be any water coming from it. If you have water coming out of the return hose then you will lose pressure at the tip. Make sense? Your pump is sending water in 2 directions because the unloader is faulty. And you cant have the trigger depressed & in bypass mode at the same time.

[Beth n Rod 1,279]

If you don't have filters for your inlet water to help keep debris and rust out of the system, this can lead to small particles getting lodged in the valves of the unloader which once it happens are not easily dislodged.

This sounds like the problem but it may also now involve the seals of the unloader.

If you are handy, you can rebuild it and replace the seals but otherwise, you may need to just replace it to avoid future problems.

I use 2 filters. 1 before the tank and another just before the pump. This gives me a two stage filtering process to keep unwanted particles out of the lines.

If you use residential water such as from wells, you may want to also install a coarse filter at the end of your supply hose where you connect to the faucet.

Rod!~

[Badzuk 16]

Its your unloader. Start your machine, squeeze the trigger & at the same time pull out your return hose to the tank, out. Their musn't be any water coming from it. If you have water coming out of the return hose then you will lose pressure at the tip. Make sense? Your pump is sending water in 2 directions because the unloader is faulty. And you cant have the trigger depressed & in bypass mode at the same time.

From my understanding this is not entirely correct. Most pressure regulated unloaders are designed to work with about a 5% bypass to help cushion the unloader and keep everything working within spec. If you have it set to not bypass any water under use then the unloader becomes incredibly inaccurate at regulating working pressure.

It sounds to me like you have a problem in a couple of areas. First if you have a 4000psi pump don't let your pressure spike above that, it is hard on equipment and unsafe.

Second if you are running the proper size tip for your machine and can only see 2900 psi working pressure then either your unloader is set improperly or in need of rebuilding or your pump is due for a rebuild.

With the wide pressure variations you describe ind your post I would start with the unloader. (again assuming no leaks in in the hoses and no air leaks in the supply AND proper sized nozzels in good condition)

If you are not comfortable trouble shooting your machine please take it to a reputable shop, 4000psi is dangerous, and I would hate for someone to get hurt due to ignorance.

[Klean Spray 14]

Thanks for all your input!

It was the unloader. I replaced today and its working like it should.

[mick m 19]

Told yuh! Score one for the Kiwi's.!! Whenever you have a problem with pressure fluctuations,it's usually because of the unloader. I have a mate who's had the same one for 11 years, [the scabby little gob****e] where as I'l go thru about 3 per year.

[CNY Hood Cleaning 27]

The other night I had my Gas PW started to loose pressure also for about 1/2 hr. It would loose about 200 to 300psi. I noticed that when the gun is pulled it was 200 to 300 below what I set it up to. Then about 5 to 7 seconds goes by and it regains the correct psi while the trigger is pulled. 1/2 hr goes by and everything worked correctly for the rest of the night. The unloader is on the pump. So is it the unloader also?

Now I flush the hoses before hooking up to the PW to minimize garbage in the pump. But I do use RV antifreeze in the pump so it won't freeze.

[CNY Hood Cleaning 27]

Oh and it's a General Pump 4kpsi @ 4G/min

[mick m 19]

Sounds like a sticky valve to do what you say it's doing. Was there any juddering in the gun? If so, it could be a restricted water flow to the pump. Or air in the supply hose. Are you working off a tank or directly from a mains source?

[CNY Hood Cleaning 27]

I had it hooked up to a main with good flow(and I used it a week before without issues) I had the hoses flushed before starting the PW. And I used the PW for an hour before I started to get this issue. Then the problem went away.

So no air in the house and no juddering in the gun.

[mick m 19]

Probably just gods way of having a bit of fun with you.

[CNY Hood Cleaning 27]

It made me very nervous.