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Pressure washer not making pressure after pump rebuild


joec2000's Avatar
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Join Date: Mar 2008
Posts: 211
FL

12-14-13, 02:40 PM   #1  
Pressure washer not making pressure after pump rebuild

Hi Everyone,

My father-in-law was kind enough to give me a pressure washer with a Honda GX390 and a CAT 66DX35G1I pump - made by Northern Tools (Northstar brand).

He said his friend ran it without water and burnt up the seals so he put a seal kit in it. After that, it wouldn't make any pressure so he gave it to me.

I ordered another seal kit, valve kit, 3.5 nozzle set (which should be correctly matched to the 3.5 GPM CAT pump), and unloader/regular seal kit. I took the pump apart and everything was in really good shape - seals looked new (replaced them anyway), valves looked original and replaced them. Plungers were not discolored, cracked or pitted.

Put everything back together, torquing fasteners according to the service manual and the most pressure I can get out of this thing is 500 PSI with the regulator dialed all the way up.

Figuring there might be something going on with the regulator, I took that apart and put a seal kit in there. The only abnormalities I could find in the regulator were a *slightly* scored ball valve - barely enough to catch a finger nail. I figured that was OK and just re-assembled it.

Still very little pressure. I took the pump apart again to make sure I didn't goof anywhere and everything looks good.

One unusual thing I noticed... with the engine off or on, not much water seems to come out of the wand when the trigger is depressed (or directly from the pump w/ the hose removed). My other pressure washer (also a Northstar ironically, from the early '90s) with an AR XMV3G30 pump will shoot water about 4-5 ft. This unit shoots it maybe 1-2 ft (if that). I'm wondering if there's a flow problem somewhere.

I took the General Pump inlet screen apart - no blockages. The unit has a fixed chemical injector on the outlet side that appears to work properly (doesn't suck air except with chemical nozzle) but the orifice inside for the water to pass through is TINY. I'm not sure if the chemical injector is factory or was added at some point but it looks original.

Any ideas why I'm getting so little pressure? There is a 4600 PSI over-pressure valve and an easy-start valve (which doesn't shoot any water at all).

Thanks!!

- Joe

 
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cheese's Avatar
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12-14-13, 05:35 PM   #2  
Hard to guess why at this point. I'd suspect one or more of the check valves I suppose. Maybe one/some are turned backwards?


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joec2000's Avatar
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FL

12-14-13, 08:26 PM   #3  
The valves seemed to only go in one way - O-ring down. How could they be installed backwards? Any suggestions for troubleshooting?

Thanks!

- Joe

 
joec2000's Avatar
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Join Date: Mar 2008
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12-14-13, 09:54 PM   #4  
Ok, I think I may have figured it out. I think the pump is plumbed wrong! There's no way it could EVER work the way it is now. Someone (not me I swear!) moved the easy start valve down to the inlet side, and put a 90 deg elbow on the discharge side where the easy start valve SHOULD be. This short circuits the discharge side back to the inlet side forcing the pump into bypass.

Looks like I need either a plug for the inlet side where the easy start valve is now (or a thermal relief valve) and to simply move the easy start back up to the discharge side!

I'm kind of embarrassed I didn't see this sooner...

 
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