Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I just picked up a used pressure washer for 10 dollars with a Briggs and Stratton 11Hp I/C engine the engine model number is 256422-0015-01.  While the engine runs it runs poorly and is hunting all over the place.  This carb is not adjustable but was clean and all of the holes are clear.  It seems to keep pulling the governor open then closed and some gas will spit out of the carb when it does that.  It also seems to be running rich but that may just be because it is hunting.

This engine is very difficult to pull through compression and will tire you out pretty quickly.   I will be adjusting the governor to see if that will help things out.

Does anyone know if this engine has a de-compressor ?

Wow, that sounds like a heck of a deal! Sorry, I can't offer a lot of info. But if it was me, I might try seeing what happens if you add choke. I presume it will get worse. But some non-adjustable carbs are apparently set to run on the lean side, due to EPA requirements. If choke helps smooth it out (as is the case on my generator, with non-adjustable carb), that might help understand what's going on (at least confirm whether you're rich or lean). From what I've heard, even clean non-adjustable carbs can still run a bit lean, due to the EPA requirements.

If you physically hold the throttle plate at a constant angle (taking the governor out of the picture), will it run more smoothly?

It looks like this is a L-head engine (not OHV). For it being hard to pull, can you check the valve clearance? I have a Tecumseh L-head whose valve clearance was off (gap was too small). That actually made the engine too easy to pull, but the valve clearance being out-of-spec in the other direction (clearance being too large) would make the compression release less effective. At least if it works like my engine. I don't know if it has a compression release. But if it's recent enough to have a non-adjustable carb, and being 11hp (sounds like a big pressure washer!), I'd imagine it would probably have one. I'd sure hope so, at least.

Check the nozzel of the carb,   the screw in long jet, brass pipe that is screwed into the same hole that the bowl nut is screwed into.  The nozzel infuses the fuel with air before it reaches the venturie of the carb.  If the nozzel's very small air holes are plugged fuel will bubble out of the jet rather than spray (causing it to run lean, lope or hunt).

Be very carefull when you unscrew the nozzel, the brass takes a fat bladed screwdriver, that is narrow enough to get into the hole without tearing up the threads. The nozzel is brass so it strips easily compared to a real steel jet or screw.   I have a special screwdriver that is short and ground down to do the job on the engine,  you may wnat to make one for yourself.  Grinding a screw driver is cheaper that buying a $20 nozzel.

Good luck,

Friiy

Let us know what happens,  post pictures.