Old engine not running, Craftsman brush trimmer

[pripyat]

My wife's grandfather died, he was a small engine mechanic, has worked on tractors since the 60s. I was told to get whatever I wanted out his shop and wound up getting a wheeled string trimmer. This is something he was working on for a customer, either it was never picked up or he was having a hard time fixing it. I pulled the carb and cleaned it, the engine starts first pull, every single time. The engine comes up to speed and then immediately shuts off. After it comes to a complete stop I pull the starter once and it does the same thing again - Starts beautifully then stops. I can overcome the governor linkage on the carb with my hand and keep the engine running by manipulating the butterfly valve. Interestingly there is a throttle cable assembly installed on the unit but I don't believe it goes to this piece of equipment. When I got the trimmer, the throttle adjustment was present on the push-handle but the cable was just hanging. He may have been trying to run the engine without the governor, directly connected to the throttle? Or possibly I am wrong and there is something else going on entirely. Can anyone point me in a direction?

Numbers off engine shield - 143294032 SER-9032E

Numbers off trimmer unit - 536.7735100 Code: 9112062922







Any help is appreciated. Thanks!

 

[RandyT]

Symptoms lead to not getting fuel after the initial prime. Sounds like a carb problem, Could be related to the bolt nut/jet. The other issues are you have a primer carb on an engine with a housing that says automatic choke. so we either have an engine that somebody has changed the blower housing which could cause issues having the incorrect model number for the engine, or somebody has put a primer carb on an engine that originally had a choke and possibly wrong carb jet size. I know the air filter isn't original to the engine. Also with the governor spring tab bent so far to stretch the spring makes me think there could be other issues as well.

 

[pripyat]

Thanks a lot for that reply. The main jet in the carb is massive compared to the other small engines I have around the garage. I used a set of welding tip cleaners in the carb ports, the main jet took the second to largest.

Any suggestions on where I should start? I'm assuming compression is good since it starts up so quickly. I can do a compression test if that would be helpful and report back. Would a video of what the governor is doing be helpful?

 

[Roadworthy]

As a last resort, I've had good luck sourcing new carburetors on eBay. With the engine number you can come up with an original factory carburetor for a surprising number of things.

 

[RandyT]

I don't remember the main jet in the nut being that big. I seem to remember that it is somewhat large as it enters the nut from the carb side, but tapers down considerable as it gets close to the bottom of the nut. Can you blow carb cleaner through the passages in the nut from both directions.

 

[pripyat]

My terminology may be off. I was referring to the diameter of the pickup tube or venturi being large. The orifice in the nut and the two orifices on the carb body piece it screws into are wide open.

 

[/pine]

Have you checked the float valve and the seat??
I too would search e-bay for a new carb parts...

 

[pripyat]

So I went out to make a video of the carb linkage. Each time I started the engine it would run a little longer before shutting off. After 4 or 5 tries it just kept running. I know nothing about these engines, I'm guessing I should manually pump the bulb to keep it running when cold? Manual choke LOL

BTW, I did check the float. I basically just made sure it was letting fuel in and wasn't overflowing into the intake when the fuel level in the tank exceeded the intake height.

I did a compression check, after 4 pulls it was up to 120psi. I'm interested now to see if I can lean the engine out a little, the plug looked really bad, dark black with lots of carbon deposit. I've got a tiny drill bit set specifically for jets, I'm assuming I can just JB weld the previous orifice and drill a new one a size smaller the same height up the bolt? Is this advisable or should I leave it alone?

I went ahead and pulled the oil drain, the oil looks and smells ancient. Going to run some full synthetic in it for a couple hours then change it again. Hoping to get a lot more years out of this little engine.

Any other advice as far as maintenance to keep this thing going for a long time to come? I'm assuming valve lash wouldn't be a bad idea..

 

[denchen]

There is usually a long, not very strong spring on the throttle butterfly, that keeps the engine running at full speed. Once up to speed, the throttle `flap` under the casing then pulls the throttle butter fly closed so slowing the engine. I carn`t see this spring on your pictures. As the engine slows, the wind pressure decreases on the flap and the spring open the throttle a bit further. What then happens is the engine settles down to its normal running speed. To control this speed, another spring is attached to the linkage and the wire speed control. By increasing the tension of this second spring, putting more pressure against throttle flap, and the engine will then run faster.

 

[pripyat]

Thanks for that reply, I am having a hard time finding a resource online that explains how the governor works. At this point it seems that the upper half of the unit is off some other piece of equipment as the engagement lever across the handle and the throttle cable is totally useless and unused.

Thanks for the input about the spring - So there should be a spring that holds the throttle open that the governor has to overcome?

I drained the oil, it was the worst I've ever seen. I let it drain for an hour and then replaced it with new oil. I ran the machine but I couldn't engage the trimmer portion without the engine dying out. I found that if I put my finger over the hole on the primer bulb, the engine rpms increased. I put tape over the primer bulb and was able to trim some weeds. I let the engine run for around 10 minutes then drained the oil again.



Sadly the second drain is pretty bad, too. The drain plug was covered in sediment, I imagine that after a couple hours of running I'll change it one more time.

 

[flyerdan]

That kind of looks like a Tecumseh mill on that, I've got a folder full of Briggs manuals but nothing for that. There is a manual for it online though.

 

[RandyT]

The governor spring is there above the throttle shaft in your first picture in post number 1. the spring pulls the throttle open and the governor pulls the governor shut, and the two fight until they find a balance at the correct engine speed. I still say that you have a carb problem. Something to check is to remove the air filter and look into the carb, and then pump the primer bulb and see if you can see gas shoot up through the top of the nozzle. If no fuel then either the bowl nut is still clogged, or you have an air leak around the primer, or bowl gasket.

 

[denchen]

It seems as you are slowly getting there. I`ve just noticed you have a fuel filter, and most engines do not come with one as standard. I wonder if this is restricting the flow to the carb. .If the fuel tank and fuel is clean, I find a lot of these engines run better without one.

 

[pripyat]

I have this rule around my garage - everything gets a fuel filter, everything uses no-ethanol fuel. It has worked well for me. I'm going to have to remove that filter anyway once I get it running right, there just isn't enough room for it. I didn't have enough fuel to rinse out the gas tank to ensure it was clean so I zip-tied the tank to the handle and used a fuel filter to rule out new trash in the carb while troubleshooting.

You guys have helped a lot. I got a ton of miscellaneous carb parts from my wife's grandfather's garage the other day. Extra jets, lots of springs and such. I actually ended up at urgent care to get stitches after an encounter with an edger but that is another story.

I noticed when running the engine that it started smoking once it got hot. When I drained the oil after I had the engine running for a while it ran out like water, it was extremely hot. I am wondering now if the oil was so nasty because of blow-by. Also wondering if the smoke was due to excess fuel.

The engine is definitely not running WOT. Based on your description of the operation of the engine, if I were to weaken the spring it would cause the rpm to increase? I'm wondering why that spring tab is bent so much. I have plenty of spare springs and can try unbending that tab. Is the goal to run the engine WOT? I'd love to get it running at the desired RPM and then adjust the jetting so it isn't running so rich.

Lastly, I flipped through the manual and it said not to use multi-weight oil. Perhaps this is why the oil was so thin when I drained it hot? Also may explain the smoking? I am using regular dino car oil at the moment, I think 10W30. I planned to use full synth rotella once I get most of the particulate flushed out.

Here is the engine when I thought it didn't run but apparently it just hadn't warmed up yet.

Shared album - Ernest H - Google Photos

 

[RandyT]

The governor spring opens the throttle, so reducing the tension will reduce the engine speed. You would need to pull the spring tighter, or in this case bend that tab even more to increase engine speed. Just make sure you know what speed the engine is actuallty running at and not just guessing. I have seen a few engines with the tab bend that far from the factory so it may be normal for that engine. Also Tecumseh should have a fuel filter built into the tank. It normally looks like a screen in the bottom corner near the fuel outlet.

 

[pripyat]

I got a bunch if miscellaneous parts from the small machine repair garage. I ended up with three different jets for this carburetor, there was a 66 in the carb, and there are two 65's. I confirmed that the 66 is slightly larger than the 65. There was a little bit of smoke coming out the exhaust when the engine was warm, I'm not sure if it is burning oil or if it was running extremely rich. I stuck the 65 in the carburetor and it did seem to eliminate some of the smoke. The carb runs great if the hole in the primer bulb is plugged. Otherwise the rpm varies a lot.

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Maybe I need a primer bulb without the hole?

 

[RandyT]

Pulled up parts diagram for the carb and it looks like primer no hole.

 

[stuckmotor]

Pripyat,

It seems as you are slowly getting there. I`ve just noticed you have a fuel filter, and most engines do not come with one as standard. I wonder if this is restricting the flow to the carb. .If the fuel tank and fuel is clean, I find a lot of these engines run better without one.

I once replaced the tiny red fuel filter on my mother's Snapper Rear Engine Rider with a larger clear one. The engine repeatedly only ran for a few minutes before it quit. When I replaced the clear filter with a tiny red one, the problem was solved. Fast forward five years or so and someone said the clear filters were made for engines with fuel pumps. Whether this was correct and whether you have the same clear filter I had, I don't know. I hope you have the good luck I had if you remove the clear filter from the equation.

 

[pripyat]

Sweet! I really appreciate it. I finally got some decent stringer line, going to run it a little and report back. Probably use RTV over the primer hole for now. Many thanks.

 

[pripyat]

Can anyone point me to a manual or give me a description of this engine? I found a ton of Tecumseh manuals but I'm not sure which engine I have.

I'd really like to check the valve clearance before I put too many hours on it. If the engine oil was changed the last time the valves were checked, it is beyond overdue.