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2019/07/28 16:13:08
reineman

Old Generac Pressure Washer Bogs When Loaded

Hello, I have this old Generac Pressure Washed, probably thirty years or so.  It is for residential use, probably ten hours a year.  Generac 6600CP, 3 g/m @ 2200psi, Model:  09617-0, Type:  6600CP
 
I've had to clean the carb several times over the years.  The washer got to the point where it would run fine for a couple hours then start bogging down as I loaded it (engaged the wand trigger).  A slight adjust of the main jet screw on the bottom of the bowl usually got it going again.
 
It finally got to the point that the carb leaks gas and needs a rebuild kit, those are hard to find, for me anyway, so I got a new carb.  The Generac web site passes you off to a place called Ordertree or Dixiesales, hard to tell.  They recommended a replacement numbered CMV16-B20 191HS, it looks similar but no external main jet adjustment.  Thirty years, new technology I guess.  The old carb is a Nikki 83666.
 
Got new air filter and carb gaskets to go with the new carb.
 
Here's the problem with the new carb.  With the pressure wand detached and water running through the pump the engine runs fine.  With the Pressure Wand attached but not engaged the engine runs fine, in other words the pump is in bypass mode and there is no load.

As soon as I engage the trigger on the Pressure Wand (apply the load) the engine bogs down and nearly stalls and does not catch up.  The governor opens the throttle fully, it's doing the right thing.  It is as if the carburetor can't supply enough fuel for a loaded engine (I'm guessing here).
 
I'm wondering if there could be an explanation for this behavior that has nothing to do with the carb.  Or is this the wrong carb for the machine?  The carb was the last thing I touched but then again it wasn't working so great before I touched it.  Also, several years ago I had a similar problem that ended up being an O ring in what I think is the pump bypass.  A wand trigger engage would spew a spray of water from the bypass and the engine would bog down.  That's what has me wondering about a problem not related to the carb.
 
There is no obvious water leakage from the pump area now and I have not taken it apart yet.  I'm asking questions here first.
 
Ideas, opinions, any comments appreciated.
1 comment Leave a comment
reineman
Looks like I get to answer my own question.
 
Turns out it was a fuel starvation problem, which is what it looked like.  The carb to manifold gasket that I ordered with the carb was the wrong gasket and must have covered up a hole I couldn't see or something.  I put the original gasket in place and the problem is gone.
 
Took me awhile but I should have immediately suspected the last thing I touched.
2019/08/16 16:11:32

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