I bought a Simpson 3000 psi gas pressure washer. When I changed the oil (first time) I found the oil does not drain out into the pan but spills over the right wheel. I called a Honda dealership and

SOURCE: pressure washer stalls

Pressure washers work under very dirty conditions, no wonder they encounter engine problems. Here are a few pointers from a former pressure pump tech. The unloader is a source of engine overloading however this can easily be checked with a pressure guage attached to the gun with a tee fitting having the guage and the normal tip used for the unit. The pressure should never rise over rated pressure. The pressure should drop considrably when trigger is released. The life of the pump and engine can be increased by setting max pressure to 75% of rating. Most engine problems are from following conditions:
Leaking or misadjusted valves; clogged muffer /spark arrester; weak spark coil that is about to fail completely; kill switch/oil sensor wiring and or sensor mal function; gas cap not venting properly causing vacuum in tank and wet or dirty air filter.
All these problems easy to check, fastest repair is to disconnect oil sensor wire to check oil safety system. Then temp replace coil with known good coil. Loosen muffer bolts to check for clogged muffler. Temp run engine without gas cap to check for vacuum. Finally if everything fails, run the engine with carb cleaner spraying directly into the intake. If the engine continues to run with carb cleaner then the problem is fuel delivey and faulty carb. enjoy

SOURCE: I have a 3000 psi karcher pressure washer with

sounds like you need a seal and bladder rebuild < if you liver in a cold environmet for winters please dont forget to winterize your washres every year before winter

SOURCE: how to change oil in a pressure washer

From the manual CleanShot 2050 Briggs and Stratton

Change Pump Oil
1. Drain engine oil and fuel from pressure washer
2. Use an 8 mm allen wrench to remove black pump oil cap between high pressure outlet and garden hose inlet.
3. Tiltl pressure washer to drain oil into an approved container until it drips slowly from pump.
4.Tilt pressure washer in opposite direction and empty premeasured pump oil bottle into same opening (a small funnel may be helpful) [THIS IS WHAT THE MANUAL SAYS-NOT CLEARLY WRITTEN IN MY OPINION OR WRITTEN BY SOMEONE FOR WHOM ENGLISH IS A SECOND LANGUAGE]
5. Install black pump oil cap and tighten firmly.
6. Set pressure washer in upright position. Add fuel and engine oil.

From the engine manual use synthetic 5w-30, 10w-30 from -20 degrees F to temperature of 100 degrees F.
Change oil after 5 hours of operation initially. Before tipping to drain oil, remove fuel from fuel tank by running until tank is empty. Remove oil cap and dipstick and tip engine. Keep spark plug side up. Or remove drain plug from the bottom of pressure washer with a ratchet and square extension and drain oil from bottom. (fuel does not have to be removed)

SOURCE: Need to know where oil

I have the same model...... it should be just underneath the unit.... it will look like a square head recessed. I used the ratchet set extension and it fit just right. I literally had to tilt the darn thing upside down to find it. Then once it was loosen a bit, I put the machine upright on the wheels again, and slip a plastic pan underneath as I finished unscrewing the oil plug, Out came the black goo.

SOURCE: pressure washer, john deere 3000 psi, honda engine

It sounds like your intake is plugged with debris. What usually happens is a water hose that has been laying around will get various stuff in it -- dirt, grass clippings, small insects (and whatever they take into it nest building). These days most homeowner pressure washers do not have a proper inlet filter, but just a screened hose washer like on a washing machine. The unloader valve can cause pressure variance, but usually not in the manner that you described. The pump is being "starved" for input water. Just use a pair of needle-nose pliers and pull out the screen and clean it or replace it.