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Discussion Starter · #1 ·
I have an old, standard, cheap-o, four stroke push mower. I don't know what kind of engine it has, but it's probably similar to a typical Briggs & Stratton. I bought it used several years ago from a friend for twenty bucks. The carb says "Tecumseh" on the float bowl.

When I start it up, I prime it a handful of times. If it's cold out, I may have to repeat this a couple times before it will run on its own. If it's warm out, the initial prime may keep it going. It will usually run a little rough/weak until it has warmed up for a minute, or so.

The other day, I was almost done mowing the lawn when it sputtered for maybe thirty seconds, then quit. I thought it might be out of gas, so I filled it up. I never could get it restarted. If I prime it, it will run for a second off the prime, but then will die.

A friend suggested that it might have a safety mechanism where it won't run if the oil is low. Well, the oil was low, so I filled it up, but that didn't fix it. I know it's getting a spark, as it will run off the prime. However, I got a new plug and fresh air filter, just for good measure. There is plenty of gas flow out of the hose. I took the bowl off and the float seems to control the flow of fuel into the carb correctly. If left alone, fuel flows out. If I raise the float, the fuel flow stops.

I took the carb apart to try to clean it out some. I put a brush, followed by carb cleaner, through the tube coming straight up from the float bowl, and through the brass tube which runs from the entrance to the throat down into the carb at a forty-five degree angle. Those seem clear. The orifice in the bolt that holds the float bowl on appears clear, but it's too small for me to know for sure. I'm not sure what else there is to clean.

It looks like the only control on the carb is a butterfly valve held by a spring. I think this must act as a governor. The spring holds it wide open. It appears to close partially after firing up. I guess the suction pulls it toward the closed position if the engine runs too fast. This valve moves freely, but has firm spring tension on it.

After all that, there is no difference. If I prime it or shoot some starter fluid into the carb, it will run for a second or two off of that fuel, then die, as before.

It seems like a fuel starvation issue, but this carb seems so simple, I don't know what else to try. Here are some photos of the carb.

Any suggestions?

Thanks,
Jay



 

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Here is a link to a breakdown of your carb. Photo number 6 shows the bowl nut and the passages that MUST be clear for the engine to run. Pull a strand of wire out of a wire brush and use it and carb spray to clean the passages in the bowl nut. The main jet which is plastic, has two O-rings that will disintegrate over time and need replacing. I hope this helps. Youtube also has some great videos on Tecumseh carb cleaning/repair. That little black plastic cap on the side is covering the low speed jet which should also be removed and cleaned. After cleaning the jet, snug it down firmly after installing, it is not an adjustable jet. If you damage the plastic cap when removing it, the carb will work fine without it.
Disassembly, Cleaning and Repair of Tecumseh Series 9 Carburetor 632747
 

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Discussion Starter · #5 ·
Fixed!

So I took the float bowl nut out yesterday, plucked a wire from a wire brush and ran it through the small hole in the nut. It didn't appear as if there was anything in the hole, but hoped it would make a difference. Then I blew through it. The air came out the other openings.

I put it back together and primed it several times. Couldn't get it to start. Primed some more. Nothing. Sprayed some starter fluid into the carb and after several more pulls, it fired. This time, it ran for maybe ten seconds. I thought it was fixed due to the relatively long run time, but then it died again.

Primed some more and more starter fluid. This time, after it started, I leaned down and pushed on the governor (auto throttle?) just to get it going full blast. This time, it kept running, even after I let go of the throttle.

Apparently, whatever was blocking a passageway in the carb finallly let loose. It's not clear (so to speak) what the problem was, but I'm glad it's going again. It's nice not to throw something away when it quits working. Fixing it feels good.

Thanks for the help.

Jay
 

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I hope it continues to run well for you. If it acts up again, I would remove the idle jet under the little plastic cap for a good cleaning and replace the emulsion tube O-rings to be safe.
 

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Your yet another victim of ethanol in your gas. That stuff will gum up a carb like nothing you've ever seen. Along with what's already been recommended, I'd put a fuel shutoff in the gas line before the carb and shut it down with that. You also want to consider a fuel treatment to help against the ethanol. I use Stabil but there are other methods too. Sea foam in your gas helps too.
If your going to store your mower for a spell make sure the carb has no gas in it.
For carb cleaning get yourself a set of torch head cleaners, it's a bunch of different sized wires put together in a kit and cost about $5. Just be real careful poking the wires into the various jets so you don't damage them.
 

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Yep, sounds like the ethanol monster got you. Just run some stabil marine treatment (the blue stuff), and maybe install a line shutoff, and you should be fine in future.
 

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Also.,.consider buying a new replacement carb on Ebay....I just did for similar fix....new carb was $15.99 including shipping...Just not worth the grief of overhauling Tecumseh carbs, since living with Ethanol fuel..IMO...plus you'll have a new flexible primer bulb...
 
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