Lawn boy 5236 has trouble starting

rev20

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Hi,
I have a lawn boy, model #5236 which is giving me trouble starting. It has been lying unused for about 10 years but yesterday when I started it it fired after several attempts. When I switched it off and tried starting it the second time, it refused. I thought the problem was the spark plug and plug wire. So today, I bought a new plug and replaced the plug wire. When I tried starting it, it fired right up! After fiddling with the air/fuel mixture knob, it died. I tried repeatedly to start it the second time and after 20 or so attempts, it fired up again. I mowed a section of the lawn for about 20 minutes and then the thing died on me. Upon checking, I realized that it had run out of fuel. I filled the tank and tried starting it again. At times, it almost seemed to start but then it quickly died away. I gave up starting it after bruising my hands.

What could be the problem with it?

My procedure for starting it:
1. Prime it 10 times
Pull the cord
FAIL
2. Adjust the idle knob (not sure if this is the idle knob but it is the smaller of the two knobs)
Prime it 10 times
Pull the cord
FAIL
3. Repeat ad infinitum
 

robinb66

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Check your top and bottom oil seals aka crankcase seals, a lot of times when a motor sets unused for any length of time especially ten years or better the rubber becomes hard on the seals and they lose there ability to seal properly. Lawnboy's are particularly picky when it comes to crankcase pressure any leaks in the crankcase will definatly effect the running and starting!! Also you might try cleaning the carb and rebuilding it, any gas at all left in the carb for that length of time is sure to have gummed something up!!
 

rev20

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Check your top and bottom oil seals aka crankcase seals, a lot of times when a motor sets unused for any length of time especially ten years or better the rubber becomes hard on the seals and they lose there ability to seal properly. Lawnboy's are particularly picky when it comes to crankcase pressure any leaks in the crankcase will definatly effect the running and starting!! Also you might try cleaning the carb and rebuilding it, any gas at all left in the carb for that length of time is sure to have gummed something up!!

Thanks! Will do that once I get a technician to look at it as I have no idea how to open the carb. Funny thing, after letting it lie overnight, this morning it fired up with the first pull! Weird...
 

Two-Stroke

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I'm curious... how did you get a Lawn-Boy in Kenya? Did you import it?

Do you have ethanol mixed with the gasoline in Kenya? If so, it's more likely that stale fuel may be a factor in this problem.

Based on what you've said so far, I think a dirty and clogged carb is the most likely problem. Is the carb metal (good) or plastic (bad)?

Also, there may be a fuel filter in the tank -- at the valve. Can you see it? If it's clogged, that could be the problem.

For future reference, you have a D-series engine. You can read about that engine in many threads in this forum -- you may want to do a search and read up.
 

rev20

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I'm curious... how did you get a Lawn-Boy in Kenya? Did you import it?

Do you have ethanol mixed with the gasoline in Kenya? If so, it's more likely that stale fuel may be a factor in this problem.

Based on what you've said so far, I think a dirty and clogged carb is the most likely problem. Is the carb metal (good) or plastic (bad)?

Also, there may be a fuel filter in the tank -- at the valve. Can you see it? If it's clogged, that could be the problem.

For future reference, you have a D-series engine. You can read about that engine in many threads in this forum -- you may want to do a search and read up.

Hehe, my grandfather bought it way back in the 70's, no idea if he bought it new or from another person.
Ethanol mixed with gasoline?? I thought it was oil mixed with gasoline! I bought oil and petrol/gasoline and mixed the two in the ratio 32:1 (as was written on the side plate).
The carb is made of metal but I haven't yet opened it as I am still new in this. Once I get a technician, we'll look at it and I'll report back. The fuel filter (if it's that thing located in the corner of the fuel tank with small holes) seems to be ok as the fuel flows out when I disconnect the black fuel pipe below the tank.
Is it possible that a dirty and clogged carb could refuse to fire up when it's hot (as I've noticed that the mostly problem occurs when the mower is hot) and operate normally when it's cold?
Anyway, thanks guys for your feedback, I'll make sure to report back on any new developments. Will also probably attach a pic or two later to make it easier to spot the problem.
 

Two-Stroke

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Hehe, my grandfather bought it way back in the 70's, no idea if he bought it new or from another person.
Ethanol mixed with gasoline?? I thought it was oil mixed with gasoline! I bought oil and petrol/gasoline and mixed the two in the ratio 32:1 (as was written on the side plate).
The carb is made of metal but I haven't yet opened it as I am still new in this. Once I get a technician, we'll look at it and I'll report back. The fuel filter (if it's that thing located in the corner of the fuel tank with small holes) seems to be ok as the fuel flows out when I disconnect the black fuel pipe below the tank.
Is it possible that a dirty and clogged carb could refuse to fire up when it's hot (as I've noticed that the mostly problem occurs when the mower is hot) and operate normally when it's cold?
Anyway, thanks guys for your feedback, I'll make sure to report back on any new developments. Will also probably attach a pic or two later to make it easier to spot the problem.

If you haven't heard about ethanol in the gasoline, I'd guess it's probably not in there. You're lucky -- that's just one more thing that can cause a problem with these engines.

If the problem only occurs while it's hot, then it's more likely that some kind of crankcase seal problem (as robin66 pointed out) could be it. That could be the gasket between the reed plate and the crankcase (relatively easy to fix) or the crankcase seals (harder to replace but I'd bet almost all engines that old need those -- but it may not be the critical problem.)

Cleaning the carb is still the first thing that I'd do if I were you. :cool:
 

rev20

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I have attached some pics of the mower. Could you please tell me where the crankcase seal/gasket is located?
SAM_0965.jpg
SAM_0967.jpg
SAM_0969.jpg
 

Two-Stroke

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I have attached some pics of the mower. Could you please tell me where the crankcase seal/gasket is located?

View attachment 19700

The seals that robin66 referred to are round, hard rubber rings (#40 on the diagram below) that go around the crankshaft. The gasket (#41 on the diagram below) that I was talking about in a previous post is located between the crankcase (#29) and the reed plate (#42).

lawn-boy5236-engine.gif

You might want to check out this page with links to a good Lawn Boy manual. It covers your D-Series engine.
 

Two-Stroke

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I forgot to say that there are two crankshaft seals (#40) -- one on top, one on the bottom.

I'm very curious about how your Lawn Boy got to Kenya. If you talk to a mechanic or parts dealer, could you ask if they were ever imported?

On the metal tag with the model number, is there a city name -- where the mower was made?
 

tybilly

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you might have a second look at that coil too,i see the outer coating cracked,that could be a reason it dies after a little time of running,after it dies after running check for spark,if no spark immediately after it dies its a bad coil
 
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