Karcher 3.97M Short cycles after trigger is released.
Unit works fine until trigger is released it will short cycle every few seconds.I don't see any leakage anywhere.Water pressure is good and filter was just cleaned. Motor switch and overload switch were just replaced as they were bad.Had pump apart and everything looked good.Pressure switch moves and operates freely.
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Re: Karcher 3.97M Short cycles after trigger is released.
There is a valve called the spill-valve. It is often called the control valve. This valve activates the micro-switch. When the gun is released, pressure builds up and compresses this spill valve. At the same time it puts off the micro-switch. This will then stop the machine. Now when the spill valve is faulty it cannot hold compreesion under pressure so it starts de-compressing and starts the machine again. This goes on in a cycle as you explained. So you have to change the spill valve. If the spill valve that operates the micro-switch is part of the upper head,...then the whole head must be renewed. Myself I rarely service Spill Valves. The best thing is to renew it. From your explanation it seems that you did not take notice of this Spill-Valve. Infact when you mentioned Pressure Switch, I do not know if you are refering to the spill valve. If you are....then saying that the Pressure Switch moves and operates freely, does not mean that it is OK.
In certain machines in the outlet...there is a small valve, coloured black and red or green and yellow. This sometimes when faulty, it gives the fault you mentioned. Sometimes an inlet valve gives the fault you mentioned. But from my expirience it is most of the time that the Spill-Valve is the fault.
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If you are referring to a well pump , short cycling could be low water level in well. It could also mean that there is too muck silt at the bottom of your well , possibles well pump is set too low. Also check the pressure tank that is connected to your supply line , if the interior bladder is leaking or the tank it’s self is leaking you won’t have proper water pressure.
Your pressure washer is either not fitted with a run/stop device in which case like mine you have to switch off within a few seconds of closing the trigger. Check your model features?
The humming noise is the motor stalled out against the pump because there is nowhere for the water to go. The shutoff is caused by the safety overload switching off after overheat.
Or, it has a pressure operated run/stop which is not working. Because water and electricity don't mix, I would suggest getting more specific help. You can download Karcher manuals /spares lists online from Karcher specialists but remember electricity is the silent killer.
It's not uncommon for duct work in an older home to Bang as the furnace cycles due to age. The humidifier banging while turning on and of is mostlikely the solenoid valve; if the solenoid is bad it is actually to your benefit to replace the entire humidifier as the solenoids are very expensive, 50%+ of a new humidifier. Plus you get the 5 year parts warranty on the new unit instead of just one year on the solenoid. If you don't want to replace the entire unit you can replace the Humidistat, and that should fix the on/off cycling, however a new humidistat is included with a new unit, which again is more cost effective. They are easy enough to replace as a do it yourselfer, especially when replacing an existing unit. I hope this helps you.
Hi and welcome to FixYa, I am Kelly
The seals do have a tendancy to harden / dry out or... corrosion prevents the unloader bypass valve from moving / operating properly. I recommend you put a little oil (2 oz maybe...) through the unit on purpose via the inlet water connection. Then connect your water hose and force the oil though the unit with the air in the water supply hose while it purges. DO NOT turn the unit on until your sure the water supply hose has purged out all air. Then turn on the unit making sure that you cycle the wand trigger rapidly for a few minutes by cycling the trigger until the high pressure hose is not so rigid then let the high presure hose charge fully again. Cycle trigger wait, cycle trigger wait. 1 second bursts until you get full pressure. Then use normally. This usually wakes up pressure washers that have been resting :)
Hi and welcome to FixYa, I am Kelly/
First off, remove the water supply hose from the power washer and locate the in line filter. Most of them are a plastic screen stuffed into the plumbing just behind the hose washer. Others have a short stand off and the filter / screen may be where the stand off attaches to the pressure washer. Others units have in in line sump that usually has a blue or red cap that you remove to clean the sump. Find the filtering mechanism(s) and clean it.
After doing this... attach the water hose loose to the power washer and turn on the water supply hose. Wait for all of the air to purge from the water supply hose. Then tighten the water supply hose. After that... Squeeze the wand trigger until all the air purges out of the high pressure hose and you get a solid stream of water with the unit off. Once you get a solid stream of water with the unit off... power the unit up and see if the high pressure hose becomes rigid / charges with high pressure. Next.... cycle the wand trigger 1 second on... and then wait for the hose to charge again. Do this multiple times. What your doing is forcing the un-loader / relief valve to stroke in the pump. Until the un-loader valve stokes un-restricted; you will have pressure problems. Next after the hose is fully charged... cycle the wand trigger very rapidly until you get high pressure each time you cycle the wand trigger. At this point your done and can proceed with patio cleaning.
Should this NOT resolve your problem.... get as much water out if it as you possibly can and pour a few ounces of engine oil into the water inlet. (Easier said than done... but you have to get oil into the pump and then let it sit over night. once you have oil in the pump pull the recoil 2 times with the ignition off just to force oil through the pump)
The next day you go through the same routine as stated above. This brings about 80% of the stubborn ones back to life again. Should it still be fussy after doing all of the above... you will have to replace the unload-er valve. If you removed the un-loader valve for any reason... you must clean out the pump housing and lubricate it and the un-loader valve with white grease (<-Available at any automotive parts source) BEFORE reinserting either the old one or a replacement un-loader valve. If you attempt to use the old one with lubrication.. make sure to remove any debris from the springs and wipe the seals clean with a PAPER towel before lubrication.
If you are sure it is not a bad o-ring and you have re-assembled it correctly then try this. Visit here: http://www.rjbowers.com/parts_manuals/partslist_1190343804.pdf Part # 8 in the pump, karcher # 9.001-187.0 includes a small bullet shaped valve. It could be leaking. It can be carefully disassembled and cleaned.
if the wash cycle runs ok then unlikely to be the drain pump or hoses. put drain hose into a bucket and check waster comes out during dry - it wont be large amounts of water. can you hear the drain pump running during the dry cycle?