Old Lawn boy will stall while mowing

trock1985

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Hi

I love older Lawn Boys, probably form the 70's or so. Mine has the old pull start etc. I bought it used a year ago and it runs well but recently when mowing it will just stall out. its not long grass, it cna be anywhere, it runs for a while and then just sort of turns off. if i give it a couple pumps again it will start right up and run for a while again and then do the same thing

i don't knwo anything about doing a tune up or even where to get parts, but is there something I can do to get it running right again?

thanks so much

not sure of the year, but it looks just like the one in the second post here. it has like half the top cover

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3358969/restored_lawn_boy_2_cycle
 

2smoked

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Hello Trock,
Your mower is approximately from the late 70's to 1980. The first thing I would check is the little vent hole on the gas cap. If it is plugged, your mower will act like you describe. The next thing I would check is the condition and setting of the carb float and the needle and seat. It sounds like something is causing fuel starvation.
 

Lawnboy77

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Okay you have a nice F series mower from the late 70s or early 80s. Sounds like you have a fuel supply issue, probably just need to do an overall 2 stroke tune up, which will include, cleaning the carb, checking for good fuel flow from the tank, cleaning the exhaust ports and muffler, possibly replacing upper and lower crank seals. These 2 strokes really need to breath well and good seals, upper and lower, clean ports and clean exhaust are keys to getting a good flow of air through the carb venturi, without the proper flow of air and fuel mix through the engine, it will lose power and die. I think you can rule out ignition issues since it starts on a prime or two after it dies.
 

2smoked

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Okay you have a nice F series mower from the late 70s or early 80s. Sounds like you have a fuel supply issue, probably just need to do an overall 2 stroke tune up, which will include, cleaning the carb, checking for good fuel flow from the tank, cleaning the exhaust ports and muffler, possibly replacing upper and lower crank seals. These 2 strokes really need to breath well and good seals, upper and lower, clean ports and clean exhaust are keys to getting a good flow of air through the carb venturi, without the proper flow of air and fuel mix through the engine, it will lose power and die. I think you can rule out ignition issues since it starts on a prime or two after it dies.
I also agree with everything that Lawnboy77 says. The F series motor is one of the best motors that Lawn Boy made, but with age, certain things need to be done with them to keep them running strong. Seals, ports, and fuel systems will all need attention at some point. The good thing about an older Lawn Boy 2-stroke engine is that it is simple and easy to work on. You can also find most of the basic parts from a number of sources on the web. If they don't run right, it's usually a problem that is easily remedied and very much worth the time and expense. I have two Lawn Boys from that era and they run just as good as new. I have cleaned out the exhaust ports and replaced crankshaft seals on both of them, along with regular maintenance.
 

unclelee

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I agree with the above advice as well. I would start with the easiest first, the fuel cap. Maybe try to run it a bit with the cap loose and see if it still dies.
Boy some of the mowers on the link you provided sure look familiar ?
 

trock1985

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Hey All

wow thats a strange post above?

when i mow some gas will spit up thru the cap?

Thanks a ton for the help! and suggestions, is there any good youtube videos on maint? or a good place to buy parts that you all use? it's my first lawn boy lol, growing up l always loved them but we never had one. when i got to the point i had my own house instead of buying a new mower somewhere i went and searched this out and love using it!

i watched a video on an older lawnboy carb cleaning and will do that, but not sure about the rest

thanks much!
 

unclelee

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Lol....I said some of the mowers on the link you provided look familiar because six of them are mine.
Lee
 

trock1985

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ha! thats a cool link and that you own them!

i cleaned the carb last night, and sprayed it al out with carb cleaner but it still dies although not as much? and dies much quicker on a hill witht he left pointing down?

another thing that was odd is the on/off switch for gas flow seems to be backwards? but i have to check that. I had it to CLOSED when i started taking the carb off and it was flowing out of the tube. i switched it to OPEN and it appeared to stop. but, when i put it all back together and kept it CLOSED thinking it was OPEN it didnt start at all. so switched it to OPEN and it started.

very frustrating.

I will keep at it today, its a new sparkplug and cleaned out carb now. it spits gas up out of the cap whem mowing and full so i assume that is open.

I havent learned more yet on this mower like seals and stuff? and have been searching the web for videos on that.

I would love to get it running great again and could really use it now.
 

Lawnboy77

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At this point I think it would be a good idea to pull the blade, blade adapter and muffler. Check the 3 exhaust ports are not restricted and also put the muffler on the BBQ grill on high for about an hour until the sludge is burned out, check out Youtube on "cleaning LB mufflers" for the how-to. The grilling technique is about the only way to clean the sludge out of those F series mufflers. While you are under there you can check and replace the lower seal if need be. Obviously if the seal has popped out of the crankcase then you will need to replace the seal, or if it shows signs of leakage, evident by oily grunge around the area. Replacing the seals are also easy, especially if you have the right tools, no sweat though if you don't have the special tools, common tools can be used, it just will take a bit longer to get the job done.

Below is a link to the manuals. ebay is a good source for parts, from my experience it's about the cheapest source for me, since I'm out here in the middle of nowhere Texas and no dealers around. Partstree is another good source I use, but will usually cost a little more. I also like to use the parts lookup on Partstree.com, I find it the most user friendly. Once you get the part number you need, then you can just google search using "Lawnboy and the part number" to search for sources. Alright just let us know if you have any questions. Sometimes these things are just a matter of "process of elimination" and all this stuff is preventive maintenance that needs to be done periodically anyway, so don't feel like you are wasting your time if this doesn't fix the problem totally, from my experience it is common to have more than one issue compounding the problem. My suspicions are that you will notice a significant increase in power by doing this cleaning of the ports and muffler. When you get a chance I would also pull the flywheel and check the upper seal for integrity to. One other thing to note on these F series engines that can hamper the ability of the engine to draw the proper fuel/air mix is a leak at the carb flange gasket, especially with a plastic carb, they have a bad tendency to warp causing an air leak which will take away from the air that should be going through the venturi and picking up fuel mix through the nozzle. Just put a straight edge on the carb flange to check for warpage and you can shine a flashlight on the back side of ruler to check for light on the opposite side, using this technique it will be obvious if the flange is warped. If you find a warped carb flange then you can use a sanding block and carefully sand it flat again.


https://lookup3.toro.com/ttcGateway/Acrobat/manuals/lball.html
 
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trock1985

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Thank you so much for that info

I will do all that and report back, I am having fun working on it and I do love these old lawn boys!

ANother question I had is, do they still make the bags and chites for this? i would like to get a bag for it as well

on replacing the seals? are there any how to's you know of? youtube videos? i am not familiar with that part of it either

thnks for taking the time. I will try and get some pics up as well for everyone so you can knwo exactly what I have

thanks!
 
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