Small engine trouble

[dstig1]

Some pics to help out. I removed the intake filter and housing to get photos that show something for most of these.







Linkage to throttle plate is the black plastic part. Only 2 holes and the linkage will not fit in the smaller one. Seems idiot proof enough.





Throttle in the full open position:


Throttle in the closed (idle) position:


A couple more views:





I still need to hit the EZGo forums. Need to start searching on that. Hope this helps someone make sense of this mess...

Thanks for any help!
-Dave

 

[GLyford]

The governor spring pressures and pivot angles were all calculated for their effect when the carb is operating correctly. If the carb is out of spec, then messing with the governor will only pull you further off course. If nothing in the governor has changed, it is probably not the problem. Things change in carbs all the time. That's my thinking, anyway?

Are the butterfly shafts loose in their bores of the carb? Could it be sticking at certain positions, or leaking vacuum? Have you checked the various fuel lines and pulse hoses for leaks (air getting into fuel lines could mess with your mixture, not getting the right pulse might mess with any pumping action). I don't know enough about the robins to know if they use a case vent hose to pressure a diaphragm like a B&S pulsajet.

 

[teejk]

Did you bend the throttle linkage rod? One of your pix suggests that. With the engine not running, does the throttle plate close entirely? If it does then I think you need a new carb...some are of the "fixed jet" variety and can't be adjusted. My old CubCadet had one of those. My Honda power washer had what looked like yours. Cheaper to replace than repair on both.

 

[Gator6x4]

The problem is with the governor. Obtain a parts breakdown or schematic of the governor mechanism. It sounds like the governor is not working at all. Start the engine and pull the governor rod leading from the carb back until the engine runs at 2800-3000 rpm normally. You should feel a slight tugging on the governor rod, if you don't you have confirmed the problem is with the governor.

Go here and find your engine model number and look at a breakdown of your engine. Subaru Robin Parts - Subaru Industrial Parts - Engine Parts & Generator Parts - Continental Engines - Greenville, SC - Orlando, FL

 

[dstig1]

Thanks for the ideas guys. Throttle plate and choke both move very easily. I don't believe this is a diaphragm type carb (like those used on chain saws, as it has a bowl). No hoses to speak of other than the incoming fuel line and a breather tube to the valve cover. Governor/throttle linkage rod was never bent, so that is not it. I am thinking Gator has got it now: It must be in the governor, no matter that it was working fine before the carb stopped feeding fuel and i had to clean it out. The linkage moves smoothly but offers no resistance or pull in any way shape or form. I always get suspicious of "new" problems cropping up when you are working on something else entirely, but I had it happen to me a year or two ago with one of my cars. Drove me nutz. I always figure that it must be something I was working that is the issue, but once in a while it is not.

I dread tearing into the governor as that means pulling the whole engine and going deep into it. But it looks like I have no choice now. That is time i do not have available in spades...

Thanks again. Will post back when I finally get to it.

Edit: Extra thanks for that link Gator. That was a new one for me that did not come up in my searches. Looks very helpful!

-Dave

 

[dstig1]

I had some time tonight so I tore into the crank housing to check the governor. Attached are a couple pictures. As far as I can tell, it is working perfectly. The weights move freely and mover the plunger in the middle freely. No binding in the mechanism anywhere I can see. Gear teeth all preset and in excellent shape, both gears. Everythign spins freely. I double checked the governor arm to throttle connection and what I said previously is true: There is only one way to connect it. The hole for the spring is too small for the governor rod to fit into, and there are only the 2 holes - big & small.

So now I am really puzzled. I guess the only thing that can be wrong is the carb, where it all started, but it doesn't make any sense to me how. I had no luck finding a service manual online for it either. I can find parts breakdowns on the repair parts sites, but no luck with manuals for this series.

Anyone have any other clues? I'm at a loss...

Here is the governor mechanism

 

[Larry Caldwell]

Typically, the governor spring will hold the throttle wide open when the engine is NOT running. When the engine IS running, flyweights (or fan sail) try to force the throttle closed. The faster the engine runs, the more force applied to close the throttle. As the engine slows down, less force is applied to counter act the governor and the throttle is allowed to open. This action is what allows the engine to compensate for different loads.

The spring only tries to hold the butterfly open at full throttle. When the engine is throttled down, the butterfly closes and the governor does nothing. If the throttle does nothing, it's a carb problem, not the governor. The first thing I would check is to see if the throttle cable is out of adjustment.

 

[TomSeller]

I had that happen once on a Tecumseh carb replacement. The replacement carb had the hole in the opposite side of the pivot point than the original. Drilled a new hole on the correct side and settled it right down of course.

 

[dstig1]

Larry - The throttle on this seems odd to me. As far as I can tell, the only thing it does is apply more spring force to the governor linkage, trying to keep the governor from closing it as easily. You can see the spring in the very front of the last few photos (throttle open and closed shots) from post #21. Throttle lever also connects to the complex mechanism you see in the early photos in #21 which doesn't seem to do anything at all. It looks like pieces that may connect to other controls for different applications. So there is not throttle cable.

I guess I have to agree that it must be in the carb at this point.

Tom - this is still the original carb, with no changes to it other than cleaning.

Thanks for the replies.

 

[GLyford]

There are lots of little holes on these carbs to get gummed up with debris and shellac. I've spent a week trying to get a carb to work on a mower...clean, air, about 3 cans of spray, little tiny wires poked into every hole I could see. A new carb off ebay and everything ran fine...the one I couldn't fix was a Nikki, which had a complicated bowl gasket, etc. The replacement I found was a walbro, simpler and ran from then on for years.