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.

 

[teejk]

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.

They do wear out especially if allowed to sit for awhile and get the aggressive cleaning. Fact of life I think. But I'll go back to a previous post...are you sure you didn't bend that throttle linkage? One of your earlier pix looked like it had a kink in it. It's easy to do in removing and replacing. But whatever...on-line stores will sell you a new carb...make sure you get the gasket!

 

[dstig1]

I can't say it isn't bent for sure, though it looks OK to me. I think it was not straight from the factory to route around the throttle lever. The bends look very purposeful, and like they are made to provide clearance to other parts. You have to slide the carb totally off the studs before you can undo the governor linkage. The governor mechanism operates freely throughout its entire range, it just doesn't want to move on its own right now for some reason. If the linkage was moving but not doing the right thing, then I would be inclined to think I bent it perhaps, but it just doesn't move at all. Probably just time to order a new carb, though I should try a bit more cleaning with this one first to save $115... I already have new gaskets. That was my first attempt to fix it, and it needed them.

 

[wawajake]

I had a Robin Subaru engine in my Cottage generator for 9 years (2001 to 2010) it was great engine, BUT since it was left sitting for a few weeks or more at times. I found that after a length of time like that I would not be able to start it. (even though I faithfully turn off the fuel each time I leave the cottage.) Soon I learned that the trick to these engines is before even attempt to pull the starter cord....take a crescent wrench and remove the carburetor bowel , shake it clean of old gas , reinstall , open the gas line valve , pull start and away it goes. I now have a Hyundai Generator , and same situation is required to start it..........even engine on my wood splitter , I find if I clear the old gas out of the carb fuel bowls (even if you just use the bowl drain plug)...they start much easier. (yes I use clean gas but I think the crappy gas with ethanol we get now days gums up quickly. )

 

[teejk]

I can't say it isn't bent for sure, though it looks OK to me. I think it was not straight from the factory to route around the throttle lever. The bends look very purposeful, and like they are made to provide clearance to other parts. You have to slide the carb totally off the studs before you can undo the governor linkage. The governor mechanism operates freely throughout its entire range, it just doesn't want to move on its own right now for some reason. If the linkage was moving but not doing the right thing, then I would be inclined to think I bent it perhaps, but it just doesn't move at all. Probably just time to order a new carb, though I should try a bit more cleaning with this one first to save $115... I already have new gaskets. That was my first attempt to fix it, and it needed them.

$115 for a carb is outrageous. I replaced the carb on my Honda last year...was only around $30 as I recall.

 

[JRobyn]

I had a Robin Subaru engine in my Cottage generator for 9 years (2001 to 2010) it was great engine, BUT since it was left sitting for a few weeks or more at times. I found that after a length of time like that I would not be able to start it. (even though I faithfully turn off the fuel each time I leave the cottage.) Soon I learned that the trick to these engines is before even attempt to pull the starter cord....take a crescent wrench and remove the carburetor bowel , shake it clean of old gas , reinstall , open the gas line valve , pull start and away it goes. I now have a Hyundai Generator , and same situation is required to start it..........even engine on my wood splitter , I find if I clear the old gas out of the carb fuel bowls (even if you just use the bowl drain plug)...they start much easier. (yes I use clean gas but I think the crappy gas with ethanol we get now days gums up quickly. )

I have the little 900w HF generator that acts that way. Figured out why. The main jet stays submerged in the tiny bit of fuel that remains after running it "dry". And on that generator, the passage in the main jet is extremely small. So it inevitably/easily gets gummed up with the slightest amount of junk in the fuel. Opening the fuel shutoff and reflooding the bowl does nothing to dissolve and rinse the gum because the passages are too restricted for there to be any "flow" until AFTER it starts.

My solution was essentially the same as yours - the little generator has a little bowl drain screw (yay!). The designers erred (IMHO) with the main jet at the very bottom of the bowl, but redeemed themselves with the drain. I added a second "solution" by soldering closed the small "minimum flow" hole in the choke butterfly. Now I can supply much stronger crankcase suction on the carb to force fuel draw through the main jet.

 

[dstig1]

$115 for a carb is outrageous. I replaced the carb on my Honda last year...was only around $30 as I recall.

I think the difference is volume, pure and simple. There are millions of those Hondas out there. This is the first Robin I have ever seen... I checked locally and online and the price was within a couple bucks of each other. Not much I can do about it if I don't have any luck cleaning this one...

 

[dstig1]

Gentlemen: Time to reopen this thread. I had picked up a new carb much earlier in the summer but had no time to deal with it until tonight. So I put the new one on. It fired right up, and immediately started to run super fast and not self-govern, same as it did with the original carb. The governor seemed to move fine when I checked that out as noted earlier in the thread, the carb has new gaskets on, and I am out of ideas. I hate to bring it to someone who will charge me 60% of the cost of a new engine, but I will either do that or just go buy a Honda or Chonda to replace it I guess.

I'm out of ideas. Anyone else got any??:confused3:

 

[RandyT]

Something to try. Move the throttle butterfly on the carb to the full open position, while watching what direction the governor arm moves. Like if the governor arm moves to the left when looking at it, then turn the shaft counterclockwise. Now while holding the throttle at full open, can be done by a throttle cable if it has one, loosen the clamping screw at the bottom of the governor arm and turn the shaft in the same direction as the governor arm moved in the previous step, and then retighten the clamp and see what happens. Maybe you twisted the arm on the shaft throwing the static governor position off.

If that doesn't fix it, that may mean that the governor gear had broken. You may need to hold the governor shaft in place while tightening because I have seen some back off because of the position of the governor arm inside the block.

 

[JRobyn]

If you manually hold the throttle all the way closed, does it idle down or still run way fast? If it will idle doing this, your problem is most likely something with the governor. If it still runs fast, the problem is likely the carb or a vacuum leak or both.

 

[MinnesotaEric]

I've got a Robin/Subaru engine on my splitter (Super Splitter) and it is now giving me trouble. I started it up a couple months back as it had sat a while and I wanted to make sure it was working. Started and ran great for 5 or 10 min. Flash forward a few weeks and I had a friend come over to help me split some wood. Now it wouldn't start. We were able to get it running with some carb cleaner shot in the intake, so it was clearly a fuel delivery problem. Finally decided the carb must be a bit plugged up, so i soak it in Seafoam for a week or two put it back together and it starts right up. But then the RPMs started to take off. I thought maybe I damaged the gaskets on the carb by taking it apart a billion times while messing with it, so I got new gaskets and put them in today (assuming an air leak after the carb, for example). Same problem - RPMs shoot way up and the governor does not seem to be doing anything. The throttle does almost nothing - it won't idle down at all. The governor linkage is moving perfectly easy and is connected correctly, but the linkage never moves on it's own now when the engine is running. I can move it by hand and it does what it is supposed to while running.

I'm at a loss. I have no idea how it could work perfectly and now come down with all these problems so soon after that. And I have no clue what might be wrong with it now. I haven't done much with small engines other than cleaning out a carb on occasion, so I am in the dark here. Anyone have any clues?

Thanks,
Dave

I don't know that carb, but it sounds like you have air leak in the diaphragm that runs the governor. You may also have a restriction in the idle jet or an airscrew.

We have endless problems with our lousy ethanol-laced fuel and tiny four-stoke jets on boat motors here in Minnesota.