HP pump pressure is low

[n175h]

I have a puzzling problem on my L4000. My General 1541 pump was very old and I had rebuilt the heads several times to bring the pressure back to 1050psi. The last time I rebuilt it didn't improve any. I did this after replacing the nozzles on the arch and the regulator valve on the pump manifold. The best pressure I could get was 750 on the arch, 1050 on the underspray.

I finally coughed up $3k for a new pump, installed it Monday and the best pressure I can get is 800 on the arch, 1050 on the underspray. The regulator is screwed all the way in for high pressure. The nozzles are about 9 mos old and the regulator about 2 years old. I have no leaks to the underspray when arch is in use. I cleaned the belts, motor, and pump pulley with Carb cleaner and no change in pressure.

I'm not sure what my problem is other than I think I replaced a good pump for no reason. Anyone have any ideas as to what to look for? I am going to replace the nozzles again when they arrive to see if any improvement. Other than that what is left to do?

David

 

[ken-pro]

You might have a leak somewhere in the high pressure line going to the overhead manifold, or to the wash arm itself. Even a leak which appears small can have an effect on pressure. Usually a bad check valve in the manifold can cause water to pour out of the relief valve located on the manifold.


Under no circumstances should you ever tighten a pressure regulator all the way to the bottom - The regulators used on the L4000 have a max pressure rating over 2000 PSI. If a couple of tips clog, (Especially the undercarriage) your pressure can climb way above the maximum recomended 1000 PSI.


To set a regulator:
Loosen Jam Nut
Set regulator to a fairly low pressure
turn on your undercarriage wash
adjust the regulator ONLY until the guage reads 1000 PSI - do not go any further
tighten the jam nut and monitor pressure

 

[phred113]

If your pressure drop is that great (1050 to 800), then you are leaking a lot of water.
This leak could be from various check valves in the system, leaking hoses, worn nozzles or the regulator/unloader. I would verify flow first to determine that the correct amount is coming out. If the flow at 'zero' pressure is correct then start looking at other system parts. A 2 year old regulator is bordering on neglect. Change these once a year like oil changes - it could save you huge in the future.

You did not replace a good pump....you replaced a General.

 

[Greg]

Hi David,
ken-pro and phred113 have good suggestions.
Check for leaks, worn check valves, and avoid bottoming out a regulator...especially if the regulator is rated to over 2000 psi.

When replacing nozzles, be sure correct nozzle size (orifice) is used.
Keep in mind; the pump only puts out a volume of water, not pressure.
Nozzles create pressure - If the nozzles are worn or replaced with oversized tips, max.pressure will not be achieved.

Greg Thoennes
Arimitsu Pumps
Sales & Tech.support

 

[ted mcmeekin]

We had to replace regulator a couple months ago. We installed new regulator and could not regain pressure. Our problem was that we had attempted to adjust on high pressure rinse--there was also high pitched wine which sounded like slipping belt. Our supplier advised that sound was unloader unloading. He said turn regulator back down then set for under carriage pressure. It worked-- wine went away and HP returned 1000.

Ted

 

[ted mcmeekin]

I left out that original problem was leak which we fixed but then the new regulator was set wrong--for HP rinse instaed of undercarriage.

 

[ProCarWashes]

Low pressure

Hmmmm, Lets see, I've had this problem before. Think...........ok check to see if the water in the tank is clear. There are several places the water could be or IS going. Which you would not know because its flowing where it can't be easily detected. First place I'd look is ..........now were was that???????? oh the check valve that is on the RO line the feeds the high pressure line. If the high pressure rinse is feeding back this line you would not know it because its feeding back to the holding tank of the RO. Also check the TDS of the RO. If the check valve is good there then next, lets see where next??????????? oh the weep line. If the check valve on the weep is bad the high pressure could be feeding back that line, even if its plastic and the valve is really bad, the excess pressure or water will bleed back into the street pressure line. Do those steps first, if its not those then report back. Now where did I put that wrench?

 

[n175h]

Sorry I haven't posted back. I've been on vacation for 5 weeks.
We checked every conceivable leak location and never could get the pressure up. At my distributor's recommendation we changed the nozzles to 1503.5 and that did the trick. I had to adjust the the regulator down a bit to avoid a psi higher than 1k. We couldn't find anything wrong with the regulator, so we didn't change it out.

I'm running 1k psi on the arch and 1k psi on the underspray. All is well again.
Thanks for your help.

David

 

[phred113]

And who says size does not matter....