4hp B&S on a Karcher pressure washer.

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2K2AcuraTL

2K2AcuraTL

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Ottawa, Ont CANADA
Hello, I was wondering if anyone could help me trouble shoot a 4.0hp Briggs&S engine on a Karcher pressure washer. This unit is has been running well since it entered in service in May ’03. It would seem from one use to the next, it has developed a throttle problem. It starts without hesitation; however, after 10-30 seconds after start-up, the engine starts a serious rev up and down oscillation.
I tried to investigate the problem by first removing the foam air filter and housing, so I can get a direct look at all the linkage. But no obvious breakage or disconnections are apparent.
I started the unit again and I can clearly observe all the linkage and spring start to swing back and forth and produce the rev up-down cycle.
I am hoping someone can suggest a plan of action to fix this pressure washer.
Many thanks
Jean L.
 
The 6.75hp Kawasaki engine on my lawn mower does that when the carb needs cleaning. I never see anything in the carb or jets, but after a thorough cleaning she runs smooth again.
 
Last edited:
Originally Posted By: 2K2AcuraTL
Hello, I was wondering if anyone could help me trouble shoot a 4.0hp Briggs&S engine on a Karcher pressure washer. This unit is has been running well since it entered in service in May ’03. It would seem from one use to the next, it has developed a throttle problem. It starts without hesitation; however, after 10-30 seconds after start-up, the engine starts a serious rev up and down oscillation.
I tried to investigate the problem by first removing the foam air filter and housing, so I can get a direct look at all the linkage. But no obvious breakage or disconnections are apparent.
I started the unit again and I can clearly observe all the linkage and spring start to swing back and forth and produce the rev up-down cycle.
I am hoping someone can suggest a plan of action to fix this pressure washer.
Many thanks
Jean L.


Tag for an answer.

My Karcher 1400 PSI electric pressure washer always surges way up and way down for the first couple of minutes of running it and then smooths out. It has always done this. Strange.
 
The 4.0 Briggs (tank mounted carburetor) is notorious for the diaphragm going out. That will make it surge up and down. Take the air filter off the carb. Take a digital picture from top view to remember what's what. Take the two bolts out that hold the carb/tank assembly on the engine. One in center close to engine ½ or 3/8 inch, one on right end, 7/16 or 3/8 inch, as you look at assembly. As you pull the assembly off, you’ll have to finagle the linkage off the top of carb. Remember how the rod and spring(s) look (picture) for reinstallation.

Take the 5 screws out that hold the carb to tank. Pull apart. Push primer bulb to get all gas out of carb. Blow it out with air if you have it, but remember to keep track of the spring on bottom of carb. If you blow compressed air into the little hole at the base of the long pick up tube, you may pop your primer bulb. Dump as much gas out of tank as possible. Blow air into reservoir on top tank or wipe out with rag as good as you can. Go to repair shop (with diaphragm/gasket) and get a new one. Reassemble and power wash away! The thin diaphragm goes on the tank, then the gasket, then the carb. Have fun!
 
Wal-mart sells carb re-build kits for those carbs. I bought 2 or 3 the last time I was there. It comes with the diaphragm, spring, mesh filter, and primer bulb. It's like $3.50. They have pictures included that show you what to do. It's all genuine B&S stuff, too.
 
If you have any leak in the wand or high pressure output the unloader will cycle causing a constant surge. If the surge stops when you pull the trigger and load the engine, thats a sign.
 
Originally Posted By: greenaccord02
Wal-mart sells carb re-build kits for those carbs. I bought 2 or 3 the last time I was there. It comes with the diaphragm, spring, mesh filter, and primer bulb. It's like $3.50. They have pictures included that show you what to do. It's all genuine B&S stuff, too.


Thanks greenaccord, lets hope that the WM's up north has them too...!! However I dont recall seeing them.. (hmmm maybe CDN tire stores might have then though....)
 
Originally Posted By: punisher
If you have any leak in the wand or high pressure output the unloader will cycle causing a constant surge. If the surge stops when you pull the trigger and load the engine, thats a sign.


Thanks punisher for the other angle. The washer still surges when the trigger is pulled. It is diminished somewhat, but it still surges.

However...... if you tilt the washer backwards (on its rear mounted wheels)... the surges are quite diminished once again..
 
Originally Posted By: 2K2AcuraTL
Originally Posted By: greenaccord02
Wal-mart sells carb re-build kits for those carbs. I bought 2 or 3 the last time I was there. It comes with the diaphragm, spring, mesh filter, and primer bulb. It's like $3.50. They have pictures included that show you what to do. It's all genuine B&S stuff, too.


Thanks greenaccord, lets hope that the WM's up north has them too...!! However I dont recall seeing them.. (hmmm maybe CDN tire stores might have then though....)


If not, check ebay. I bet you can get one for a fair price shipped.
 
Originally Posted By: greenaccord02
Originally Posted By: 2K2AcuraTL
Originally Posted By: greenaccord02
Wal-mart sells carb re-build kits for those carbs. I bought 2 or 3 the last time I was there. It comes with the diaphragm, spring, mesh filter, and primer bulb. It's like $3.50. They have pictures included that show you what to do. It's all genuine B&S stuff, too.


Thanks greenaccord, lets hope that the WM's up north has them too...!! However I dont recall seeing them.. (hmmm maybe CDN tire stores might have then though....)


If not, check ebay. I bet you can get one for a fair price shipped.


Well, I made it to CDN Tire and found -1- kit. It had the diaphragm, spring and spring cap. Thats it, and it was $6.00. :-(
(typical fashion how we get skewed here up north...get less - pay more..)

Now I need some time to get this done...

J
 
If your kit has a spring, cap, and diaphram with a choke rod sticking through it, you have the wrong one. If its about 1 inch X 2 inches (rectangle) with spring and cap, it's wrong. The kit you need only has the thin diaphram and the gasket. Take it off and bring it with you to the shop. Remember to put the diaphram on, then the gasket, then the carb.

Send me your email and I'll send a pic. [email protected] wife.

Whoo Hoo!
 
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OK... the kit I have is kit #5021 - Carburetor Kit - " fits 2 trough 5HP engines" as it says on the package.
The diaphragm is approx 1" x 1.5" with 2 -U- shape cut outs and 7 screw holes. Otherwise the diaphragm has no other holes.
email sent... Many Thanks
J
 
Last edited:
Job DONE...!!

It took me about 40min to do this, mainly because of being extra cautious and the leaning curve.
And its running just fine again.
Thanks to all of you for your insight and Yeehaw for the extra efforts.
Now I am gone to get a refund on that (inappropriate) 1st kit I got..
Cheers
J
 
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