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B&S 13.5 HP only runs w/ choke


i6pwr's Avatar
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03-28-09, 05:09 PM   #1  
B&S 13.5 HP only runs w/ choke

I read the similiar thread below, very similiar situation.

This is my sis's rider that was left w/ the house, by the size of the vines tangling the tires and the apple juice of fuel that was in the tank, it needed some TLC.

Drained the fuel, filled with fresh.

Replaced the fuel lines and filter, removed the bowl and cleaned, if it started I would be amazed. Cleaned the float and jet holes w/ cleaner and put it all back and the fuel wouldn't flow into the bowl. I removed the bowl, fuel line and sprayed cleaner in the fuel inlet, then applied compressed air and after a few minutes of soaking I could blow out the inlet, I was getting air now at the bottom of the float.

When it started, it ran but shortly after it would only run on choke. The large black tube coming from what I believe is a fuel pump to the base of the air cleaner is puffing air when running, it's the only tube coming from it.

Air filter is clean, but when it's running it barely pulls fuel through the line..just a few drips here and there. I know it won't flow crazy fast but it's not pulling it like it should.

When you raise the float, it shuts off the fuel but it's a very damped feeling when raising the float, like an oil-damped shock absorber from a model car but it shuts off the fuel with minimal pressure.

Is the pump-like thing the culprit or is the carb toast? It's been sitting for likely 1-2 years.

 
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03-28-09, 10:30 PM   #2  
Sounds like you just need to get some carb cleaner and clean the carb out properly. The black hose you mentioned is the breather hose from the crankcase breather. it is supposed to puff air like you described.


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03-29-09, 06:29 AM   #3  
I was thinking the same thing as Cheese. You need to get a gallon of dipping carb cleaner. Gunk brand is readily available at your local Auto Parts store. With dipping basket it runs about $35/gal. Completly take apart the carb making sure to remove the seat and all adjusting screws if it is an adjustable carb. Put the carb and main jet in the cleaning solution for 1/2-3/4 hour. Rinse and blow out every hole in the carb.
It would help a lot if you could post the engine numbers.

 
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03-29-09, 07:19 AM   #4  
Engine #'s are:
Z8R707....first digit sure looks like a "Z" rather than a "2".
1120-E1

Would it be better to get a rebuild kit or does it need to be soaked anyway?

Apparently the first digit is a "2", how do I determine which carb I have?

 
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03-29-09, 08:11 AM   #5  
Your engine number is 28R707 code 1120-E1.
Carb needs to be soaked to get to the tiny internal pin holes. You can not see all the internal pin hole passage ways. And then it needs a new carb kit.
To get the correct carb kit, you need to know which carb you have. It would be best to bring the carb into the shop you are getting the kit from as this engine used 15 different carbs.
The name of the carb (Nikki or Walbro) should be on the side.
Nikki kit # 694930. B&S used 14 different Walbro carbs
Walbro carb # LMT 133, 134, 135, 136, 166, 168 use kit#499231
Walbro Carb# LMT 58, 59, 60, 61, 62, 92, 93, 94, 95, 96, 108, 111, 162, 165, 169 use kit # 499220

 
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03-29-09, 08:50 AM   #6  
I am not a fan of soaking, dipping or submersing a carburetor in cleaner. Most engine manufacturers DO NOT recommend submersion carburetor cleaner. Briggs & Stratton recommends using an aerosol cleaner followed by compressed air for blowing out loosened debris and solvent. Many shops today use ultrasonic cleaning which is possibly the most thorough cleaning available.

In my business, I prefer to use an inexpensive aerosol carburetor cleaner sold by at Auto Zone parts stores. It is an Auto Zone brand “Valucraft Carb Cleaner” Part Number: AZ-4, 13 ounces in a yellow and black aerosol can with a red plastic cap. I have been very successful in cleaning carburetors often without removing them from the engine. Valucraft Carb Cleaner will melt and wash away varnish. Be sure to blow passages and everything else out after cleaning. If I have a carburetor that is extremely dirty and varnished, I take it to a shop that owns an ultrasonic cleaner and pay them a small fee to clean the carburetor.

If the carburetor on your engine uses welch plugs to cover fuel passages they MUST be removed to effectively clean the carburetor.

WARNING - Do not get “Valucraft Carb Cleaner” in your eyes or on your skin. Use a full-face shield for eye and face protection. Wear protective gloves. The cleaner will damage rubber so remove rubber carburetor parts to prevent damage.


This link details how to clean a carburetor:
What are the procedures to follow when overhauling the <i>carburetor</i>?

http://www.briggsandstratton.com/pdf...100/MS4990.pdf

http://www4.briggsandstratton.com/mi...n%20System.pdf

 
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03-30-09, 12:28 PM   #7  
I pulled the carb today and there was trash in the bowl again so the fuel is obviously knocking the varnish loose. I removed the brass jet in the center of the bowl and it did have alot of gunk in it.

Cleaned it out, sprayed all the tiny passageways I could find and it runs much, much better...however it surges a bit.

I can get it down to a low idle but it surges, at full throttle it surges about the same also. The only adjusting screw I can see is the black plastic "limited adjustment" screw.

What's the best way to adjust the carb? I may need more cleaning but it appeared to be clean.

Carb is the Walbro newer model with the adjustment screw I described.

 
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03-30-09, 12:49 PM   #8  
Did you remove the welch plug and clean behind it? This is discussed in one of the links I provided.

Your problem may very well be under the welch plug. The welch plug covers fuel ports that if clogged WILL cause surging.

 
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03-30-09, 03:26 PM   #9  
If you are getting "new" trash in the bowl you need to replace the fuel lines and clean the tank or it will continue to happen, the new junk comes from the tank through the fuel line, to the bowl, so one of those is crusted with the old fuel varnish. Have a good one. Geo

 
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03-30-09, 03:46 PM   #10  
Before I started it the first time, I made sure the tank was clean and the fuel lines were replaced. The aluminum housing around the float is where the varnish was, with it on the engine I couldn't see the other side.

Where is the welch plug and is it a permanent thing if I remove it or can I replace it.

I will research it but in case I don't find anything on it.

Thanks again.

Added a pic of the carb.



Last edited by i6pwr; 03-30-09 at 04:16 PM.
 
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03-30-09, 05:06 PM   #11  
If you will read and follow the instructions at this link you should have no problem. Every detail is here and instructions are step by step.

Good luck

What are the procedures to follow when overhauling the <i>carburetor</i>?

 
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03-30-09, 06:09 PM   #12  
Thanks for the link, I think I did everything except for the plug.

I know it's obvious to most, but where's the welch plug?

If it's the round silver object in the top left, I don't think it's coming out.

 
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03-30-09, 06:35 PM   #13  
Go to the heading titled Disassembling A Float-Type Carburetor in the link below. In step 7, welch plug removal is explained and the welch plug is clearly shown in (image D).

You will need a part number 695005 welch plug.

Sorry, I cannot make it any clearer than this. Solicit help from a friend or take it to a repair shop.

What are the procedures to follow when overhauling the <i>carburetor</i>?

 
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03-31-09, 04:08 AM   #14  
I understand the simplistic nature of the thread and image D, I just couldn't find the welch plug. Low and behold, it's behind the bolt that attaches the carb but it's not visible with the bolt in place. So I was trying to determine which "plug looking thing" was the welch plug.

Not my carb in the tutorial so I wasn't going solely on the pic but didn't want to start knocking out or punching holes in the carb body.

 
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