Engine Running & Carb Problem


Old 04-06-04, 10:54 AM
Thread Starter
Join Date: May 2003
Location: Brookfield Wi.
Posts: 137
lawn boy 6.5

I have a lawn boy mower 6.5 that the cylinder fills up with gas when not running and blows out the exhust when I try to start it .I noticed if I loosen the screws that hold the carb on it runs fine until the scews tighten back up
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Old 04-06-04, 02:20 PM
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Join Date: Feb 2003
Location: southern louisiana
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The reason the cylinder is filling with gas is because the needle in the carburetor bowl isn't seating properly. One cause would be a cracked float, to see if this is the problem, shake it, if you hear gas sloshing around in it, replace it. The second cause is trash could be stuck on the needle or seat. Clean then really well. The float should move easily up and down.
Old 04-06-04, 02:55 PM
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Hello; gbpack

If there is gasoline blowing out of the muffler and the engine is a two stroke, gas is likely to be in the crankcase. If the engine is a 4 stroke, gas will also be in the crack case.

In the 4 stroke, check the oil for gasoline. Likely to be some of not a filled crackcase. Oil will needed to be changed.

Most likely reason why engine runs well once the carb screws are loosened is, it lets in additional air which thins out the gas to air ratio.

As mentioned in the prior reply, chances are the carb is the problem. Cleaning it out, leveling the float and checking the needle and seat should help to resolve the problems.

Be sure the air vent hole in the carb is not restricted. Air hole will be on top of the carb body.

Most likely I haven't covered all of the possibilities. The other resident small engine service and repair professionals in the forum may be able to offer additional suggestions, advice & help.

Check back on your question several times over the next few days for additional replies.

Small engine repair parts, generic repair manuals and additional help are all available at all local small engine repair shops and or lawn mower repair shops in your area. Shops and dealers are listed in the phone book directory.

If you need further assistance, use the reply button. Using the reply button moves the topic back up to the top of the daily topic list automatically & keeps all communications in this one thread.

Regards & Good Luck. Sharp Advice.
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Old 04-06-04, 03:18 PM
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Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
Sounds like you have a newer Lawn-Boy with a Tecumseh engine. Provide me with the engine model and serial numbers and I'll provide you with a list of parts you will likely need. You can then see your local Tecumseh engine dealer for these parts. Furthermore, I strongly suggest you soak your carburetor in a cleaner in order to remove any varnish build-up that has likely accumulated. Here's a big secret I hope none of my competitors read - go to your local Napa store and buy a gallon of Carburetor Cleaner item# 6401 and soak your carburetor for 20 minutes. NOTE: This is a very strong solution, rubber and some plastic parts may be compromised if soaked too long. If you're uncomfortable doing this, take your carburetor, in hand, to your local OPE shop and let a professional take care of reconditioning it.
Old 04-12-04, 03:23 PM
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Location: Upstate New York
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Hey lawn boy!

How'd you make out with your trouble?
Old 04-23-04, 07:37 PM
Thread Starter
Join Date: May 2003
Location: Brookfield Wi.
Posts: 137
Originally Posted by puey61
How'd you make out with your trouble?
I used it today but I had to refill the gas it drain out through the carb.Maybe the float needs to be adjusted.do you happen to know the setting for it.Oh, it did run fine when I used it
Old 04-23-04, 10:39 PM
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Hello gbpack1950!

Did you clean the carb, and replace the needle and seat? That's where the problem is, unless the float is not floating anymore.

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