$25 Pressure Washer

Governor needing "adjusting" is highly unlikely...they generally just sit there and do their thing. I've only ever had to work on a Honda Engine governor about twice...one was just plain worn out, mega hours. The other one had to be readjusted after the customer adjusted/fouled it up.
Now if someone messed with it in the past (adjusted it wrong) it would run too slow/too fast, but I don't see how it would make it surge with no load...unless...hmm, is there a small spring on the governor linkage? There is supposed to be a spring to keep the "slop" in the linkage from causing surging.
Also, have you taken a reading on the secondary side of the coil? (spark plug cap to the coil) Every once in a while, a spark plug cap resistor will go bad and cause issues...I doubt that's it, but its worth checking. Off the top of my head the coil/cap combo should be 7-8k ohms.
2010_11_08 US GCV135 160 Engine Adjustment Information.xls
What's the serial #? There about 20 different GCV160 parts diagrams, differentiated by serial number.

 

No kidding. The splitter has the same/similar engine. It’s been sitting for a month plus…fired up first pull with choke and runs perfectly.

I’ve worked on old Briggs that haven’t needed this much attention.

 

Thanks! I’ll add those checks to my list; easy enough to do.

I har you on the governor. I’m not a mechanic by any means, but I’ve never had to mess with one in all the small engines I’ve tinkered with. I’ll adjust it and see what happens. Who knows, I may be tearing this thing down for a full overhaul based on the next things to check and test out.

Edit: I’ll look and see if I can find the serial number on this to help with diagnosis.

 

Big surprise…no change with the governor spring. I did pull the coil, cleaned the flywheel magnets, gapped the coil and no change there.

So I’m at the point of diminishing returns. I think I may return the parts that I can, list it for $50 and see what happens. It does run and the pump works. And hey, it has a Honda engine.

Two AI models have different approaches; one still has me messing with the govenor, the other thinks it may be the govenor weights inside the case.

I’m open to other suggestions.

 

What's it do if you try to hold the governor still?

 

It runs just fine. To me, that seems to rule out a carb issue..or possibly spark? I would think that if another issue was present, holding the governor still would cause the engine to stumble or run oddly.

 

I would tend to agree

 

Maybe it is the weights inside? Not sure I feel like digging into it that deeply.

 

I suppose anything is possible, that would be so very unusual though.
I would say it would have to be something in the movement of them...worn/sloppy, or sticky somehow.
The internals on these lil engines are pretty simple really, nothing like tearing into a modern car or motorcycle engine.

 

Part of me want to tear into it just to say I did. Then I look at how many irons I have in the project fire right now!

 

So you said running it on partial choke made no difference, right?
Still shocked this isn't a carb issue...

 

Correct. But it was idling fine..which is odd. This really has me stumped, because I’m still focused on the carb as well. Maybe I’ll swap the aftermarket one on again and see.

Same engine as the wood splitter and that thing runs like a top. Starts first pull after sitting for weeks.

 

I pulled the governor and unfortunately, no smoking gun. Everything was intact and moving freely. I gave it a good cleaning and no change.

So at this point, I’ll put it back together and see what it does. I’m leaning towards buying a unit from Marketplace that has a bad pump, but a good engine.

 

Long shot that hasn’t been mentioned yet I don’t think, but is there any chance that there’s a compromised wire(s) somewhere that could cause an issue?

 

Once you unplug the on/off switch and the low oil switch, there isn't really any wiring left

 

Good question! I had unplugged the kill switch to isolate that. This one has me stumped!

 

Just because my gut, and experience tells me this is still fuel related, I will mention again taking a spray bottle and misting a little gas on the air filter while its running, see how it acts.
I mentioned it in passing earlier, but didn't elaborate on it much...

 

I agree. And you know, I never checked the fuel shut off. I wonder if it’s plugged up just enough I to slow the flow and cause the hunting. Guess I’ll get this back together and test it again.