Pump will not shut off when the sprayer nozzle trigger is releasd on my McCullogh electric press. washer mdl fhh18a

Check all ends of your power wand. there should be a little filter and if it gets plugged the motor will shut down. Check both ends of your wand. The sprayer end should come off and mine has a filter if you take the sprayer end off.

I had the same problem on an electric and a gas pressure washer.

Once you know how your PW works the solution will become clear. All electric pressure washers are basically the same. The all pivot and revolve off the same basic set of patents and design.

You hook up a hose and turn the water on - pressure is applied to a valve in the pressure washer. Squeeze the trigger and water comes out of the wand / spray gun / nozzle etc. At that moment the pressure valve senses a drop in pressure and "knows" that you are spraying water and activates the motor which increases the pressure to ~ 1500 psi. Once you let go of the trigger the pressure increases in the unit (water has no place to go) and either that same valve or another sensor shuts the motor off.

Why does this sensor fail?
1. water is a mess - hard water, minerals, rust, bacteria grows in the water and forms a stick mess on the parts. All of this can prevent the valve from moving (same thing happens on gas power washers).

2. In places where the temperature falls below freezing the unit must be stored inside or trapped water can freeze and crack or damage parts.

Remember, Ideally a corrosion inhibitor / pump lubricant is supposed to be run through the pw after each use and especially if it will be stored (winter season). Most people don't.

SOLUTION:
1. you will need to download a manual for your unit (free from the mfg website) take off the plastic cover and remove the sensor and clean it mechanically with a brush & any degreaser like simple green etc.. Test the unit with the cover off. It might need to soak over night in a jar. If it still fails, which is quite likely, you must order the replacement part - usually costs about $20. Some "brands" don't sell that exact sensor and you must buy the larger piece that it screws into which will raise the cost to about $30+.

Note to gas pressure washer users:
There is a youtube video that shows how to clean the valve body and if it is done correctly the washer will work same as new without replacing any parts.

I would guess there is a leak somewhere inside the unit that is spraying water on some electrical component and causing a ground fault.

YES

You will need to adjust the nozzle on the end to low pressure.

Hi Brian. Welcome to FixYa I am Kelly. This sounds as if the bypass / unloader valve is stuck in place and the pump id dead heading causing the unit to shut off. (There is most likely some corrosion in the unloader / bypassy valve assy / housing. What you can try is pouring at least 3 oz of oil into the water inlet assy and briefly.... like VERY briefly switch the unit on then back off. Then let it sit over night. The next day connect everything for normal use then turn the unit on again briefly. Use a bucket to PURGE the oil that you put through the system by squeezing the wand Power SW Off until the oil purges. Then switch the unit on and rapidly trip the trigger at 0.5 sec intervals or less. If it trips off wait 5 mins and try it again. Do the rapidly tripping the trigger on the wand routine for about 20 seconds. Your forcing the bypass unloader valve to cycle trying to clear out any debris / corrosion.
This works often and well. There are exceptions. Hopefully it will work for you.

Thanks for using FixYa.

Kelly

Hello awseibel:

1. attach your garden hose to the inlet (at the back I believe)
2. Attach high pressure hose with gun wand/nozzle
3. turn on the water
4. plug into electrical outlet
5. turn on/off switch on
6. spray away
7. Any non-caustic soap can be used
8. You must set the machine on low pressure to apply soap.
   

My Kracher 2500 pressure washer has no pressure unless I remove the nozzle. If, I remove the nozzle and pump the trigger several times and quickly replace the nozzle it works fine until I release the trigger. Karcher (online) suggested I remove and clean the unloader which I did. It still doesn't work correctly. What another solution?

On hooking up to a water source and plugging it in to an electrical outlet any attempt to test the unit is unsuccessful to include having the on/off switch in either position. With the switch in the on position pump does not operator. The last time I used the unit was July of last year and prior to storing it I did drained the hose.

No need to re-invent the wheel when building your trailer mounted sprayer. Your local Northern tool Store, or at the address below,

http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_166839

you will find all the parts that you will need to complete your project. I have purchased several different types of sprayers, tanks, pressure pumps and parts from them over the years. They have a helpfull staff and most parts are in stock. Take a look at ready made trailer mounted sprayers there to pattern yours after then design in your special needs.
My first portable sprayer was made from four 55 gallon drums loaded onto the back of my pickup. For the pump I used a modified 2" trash/water pump reduced to 1' pipe then seven nozzles. Worked great however 220 gallons of water did not last very long. Problems began with the weight of water in large quantity. I decided I needed about 1000 gallons and found that I needed to deal with about 7500 lbs of weight. Oh well, enough already, good luck with your project and email if you have questions.