Machinery

Small engine only runs with choke wide open

carbs,choke,gas engine,Briggs and Straton 201417
Briggs and Tratton small engine 201417 carburetor repairs

Our Bearcat wood chipper 70085 has been sitting for over a year. The deep cycle battery died a couple years ago so I rely on the pull start, which works great. Until the other day.

 

 

 

 

I did get the engine to start but once the engine warmed up, I could not turn down the choke otherwise it would stall. So there’s a problem with the fuel or the choke itself. The choke appears to be fine. “Time to strip down the carburetor”  was the advice of brother Mike, the family guru for all things mechanical.

So I started with taking off the filter to look inside and make sure the choke was operating ok. It was fine, so it was time to consider a fuel problem.

Disclaimer: I’m not a mechanic. Neither do I claim to be. So take the advice here for what its worth… free. You get what you pay for 🙂  I think I am right but am willing to admit I’m wrong so if you read something I said that is incorrect, by all means, post a comment below and I will correct it.

Below the carb is a float bowl. Its where the gas sits while travelling from the gas tank to the   carb. Its called  float bowl because in it is a round, white piece of plastic that floats in the gas and acts like the shut off mechanism in a toilet water tank.

A small brass tube runs from the float bowl up into the throat of the carb. Fuel is drawn up through a small hole in the tube and sprays out into the passage of the carb.  The fuel mixes with the air as its drawn into the engine. That’s my understanding of how it works.

(Click on pictures for larger images).

carb repiars,small engine,Bearcat chippers 70025
Examining the choke on the carburetor

The parts of the float bowl are below. There are the 2 mounting screws, the aluminum bowl (left) with spring (inside). And the white plastic part is the float mechanism. There is one more part and its a small brass part that you can see in the picture, in the center of the float mechanism (small dark spot).

carburetor repairs,diy,bearcat wood chippers
Examining the parts of a carb float bowl.

With the float bowl removed we can now see the underside of the carb (below).

carb repairs,float bowls,parts,small engines
float bowl removed

In the case of my repair, the small brass part in the float mechanism had some grungy stuff on it. Upon removal, I could see that there is a hole in this little part. A small hole at that. I had to use a needle to clean it out. So its all cleaned out and I can clearly see a hole in this part. My guess is that this little part is where fuel is drawn up into the carb. Hopefully problem solved.

carb float bowl repairs
carb float bowl repairs

After lunch, went out and first pull, perfect 🙂 Choke works fine now.

 

 

A Newfoundland born Canadian with a life long interest in woodworking, baking and anything else that peaks my curiosity.

2 Comments

  • Jim

    Jim,
    This was exactly the issue with my BearCat 8hp. In my case I saw the fuel lines all cracked while inspecting it having not used it for a few years and was full of real old gas (getting ready for cleanup tomorrow after Arthur) On the bottom of the tank was sludge so emptied the tank, replaced the badly cracked fuel line, cleaned the carb and bowl (more sludge what a mess!) and treated the fuel with sea foam, still no start unless I primed the carb with gas and the carb cleaner spray was feeding the system. As soon as I stopped spraying it would stall… I saw that brass tube which must be the fuel supply jet wasn’t spraying anything (not a mechanic either) and when the machine stalled I checked and it was dry. I really thought the machine was toast by then and was about to give up. But when I googled and found your post. I checked and sure enough that little pinhole was plugged.. I didn’t even notice it when I had the float bowl off the first time to clean out the other 2 holes and the float plug that were obvious.
    Thank you for posting this. I’m back in business for tomorrow!

    • Jim Barry

      Its a good feeling when you can troubleshoot your own engine problems. Cheaper than having to drag the Bearcat to a small engine repair place or dealer and certainly cheaper than buying another one. What sort of Bearcat do you have? I recently added a tow bar and wheels to mine.

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