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Starting problem with B&S 31H777 engine


criengineer's Avatar
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02-12-09, 06:13 PM   #1  
Starting problem with B&S 31H777 engine

I have a sears lawn tractor with a Briggs & stratton 18hp engine. It will start but only run for 1 - 2 secs. The engine is equipped with a Walbro LMT carb which I have removed and fully cleaned. The bowl fills and the anti-back fire solenoid is functioning as per specs. The Engine will start and continue to run as long as I inject raw gasoline into the air intake. It stop as soon as I no longer do so. I don't think the card was as clean as it is now when it left the Mexican factory. Any ideas?

 
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02-12-09, 07:55 PM   #2  
All you have between the float bowl of fuel and the carb throat, which is where you have been shooting fuel are the jets. sometimes air leaks at the carb/manifold can mess things up.

Will it run on a partial choke?

 
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02-13-09, 06:36 AM   #3  
Thanks for the reply. No it will not run at partial or full choke. It only will run if I provided fuel by way of the air inlet. As per normal trouble shooting methods, I pour a little gas in or use a syringe to inject a flow of fuel. It will only run as long as I do so. I also performed the Craftsman recommended test of removing the spark plug and injecting fuel directly into the cylinder. Just does not seem to suck fuel from the bowl. I order a rebuild kit yesterday so as of now that will be my next step.

 
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02-13-09, 11:17 AM   #4  
Check your main jet to make sure it's seated tightly in the carb casing. If you have a leak there it won't pull fuel up.

 
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02-13-09, 10:30 PM   #5  
Drop the bowl and look at the stem that drops off the carb where the solenoid screws in. Does it have a small brass jet screwed in the side of it near the bottom? If so, take it out and clean the hole in it.


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