Pressure washer carburetor adjustment

[RichTes]

Picked up a project pressure washer. No hose or wand and didn't run. Has a Honda GX390 13HP and a CAT S4F 4GMP pump.

Put a new carb on it and started on second pull and ran OK. The motor manual talks about adjusting the idle. Can you adjust idle with the pump on? Seems like it's full out or off and not much in between.

Thanks,
Rich

 

[aircommuter]

usually when the gun is closed the pump bypass opens and they idle, not sure about yours.

 

[gdocktor3]

There is a member on here who is a Honda tech and knows quite a bit about pressure washers. I've seen him post on other similar threads. I will try to find his name.

His user name is justme- with the dash. If he doesn't chime in before you read this, I would recommend shooting him a pm. Seems like a very knowledgeable individual, especially on small Honda motors and pressure washers.

 

[justme-]

Always run the pump with water hooked up and on. Idle adjustment is moot, pressure washers almost never idle. Correctly stated, when the gun is closed the unloader allows water to bypass the pump...I've only seen 1 unit with an idle control circuit from the pump, which was ironically a ryobi with a junk devilbiss pump.

Engine idle speed should be about 800 rpm, but again it's not critical. Idle is the black plastic screw, high speed is the metal screw that stops the throttle lever. I've seen some preset throttles similarly done to generators, which have no throttle lever.

 

[redmondjp]

usually when the gun is closed the pump bypass opens and they idle, not sure about yours.

I've never seen this on a pressure washer - usually the motor runs at a continuous speed. I've got a big unit, with a Vanguard 18HP twin running a General pump 4.3gpm 4k psi. It has a throttle control on the engine but it doesn't change the RPM when it goes into bypass.

Are you perhaps thinking of gas-powered air compressors? I've seen an idle-down feature on a couple of these, where they use a tiny air cylinder which kicks the engine RPM up and down.