Pressure Washer Tip pressures

[lee]

I was assuming you had already checked and ruled out cracked pistons, too large tip size, low loaded engine rpm, restriction in the chemical injector etc. I took the chemical injector off an unloader the other day and it was so corroded there was only a pin hole opening through it. I just got my pressure gauge last year and was going through the same learning curve you are re. what the pressures should be. From what I gather on a commercial pump if everything is right you should be able to turn the unloader down with the trigger pulled and see the pressure climb until it hits it's rated operating pressure. Then when you release the trigger the pressure will spike 400 psi or so over the operating pressure you set. Whenever you see the operating pressure top out stop turning the unloader as you want it to bypass when you release the trigger and continuing to turn the unloader after the pressure has topped out may not allow it to open the bypass. I would think that CAT pump would do every bit of what it's rated at.

[KE4AVB]

Tnx for the info.

This particular commercial customer never releases the trigger he keeps all of his pressure washer wands taped down. I untape them while at the shop for testing and then retape upon delivery. My other commercial customer does 2 story work and hasn't any problems. The pump I currently working I did 4 yrs ago.

I did find some info in regards to tip size and he is running a size larger (4.5mm) than the recommended 4.0 mm so I did pickup some 4 mm tips today if nothing else for my own use during the testing phase. At least I got a few days before the packing comes in.

It can be rather fun learning on the fly especially when other is work coming fairly constant now. Sure keeps me on my toes.

[NO0C]

I'm a day late, but I was looking at an AR service manual and when they speak of adjusting the unloader.

After adjusting unloader: "Release trigger and make sure there is minimal spike (200-300 psi) (Repeat this step two or three times)."

[KE4AVB]

Well rebuilt the pump head today. Packing was worn. Pressures were still too low around 1500 so I went ahead changed out the 40045 tip to a new 40040 and the pressure immediately jumped to over 3000 psi and I definitely hear there was heavy load on the 390 engine. I would not have thought a difference of .5 gallon would make such a big difference.

Now to strip the old pump head and find out why the valve cap jammed at the last .020".

Also have found what all the problems with the donor pump head are. Stuck valves, bad pressure relief (regulator), bad packing, and bad thermal relief. Then I still need to open the crankcase to see if there is any rust damage in there since the pump with broken oil cap was sitting in a 5 gallon pail half full of water.

[lee]

My RKA 4G40 pump is set to 4000 psi with the #4 tip. Just for kicks I swapped in a #4.5 tip and the pressure dropped to 3300 psi.

[KE4AVB]

Something to note that I was reading is that we need to be testing pressures with a Zero Degree tip of the correct size. Different tip angles can affect output pressures. Since I was using a 40040 (40 degree) it might explain the slightly lower pressure too.

It seems that I got to learn a proper way to use my new found toys when testing. Definitely going to help in troubleshooting of these pumps. Definitely help me to pin point the problems with the two pump I had here at the same time. Glad the customer was willing to let learn this new procedure on his pumps.

Now I got to get myself a GX390 or similar engine to operate these pumps during the test phase though I prefer the customer to provide his setup. As with this customer he was also having engine problems. Leaky flywheel side oil seal and hard starting. The hard starting especially when hot was because the spark plug was gapped at .060. from normal plug tip wear, probably the original plug. We will be a lot happier camper when get washer back.

I need to get my own pressure washer.