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I got a lawnmower from my friend, he said it wouldn't run. But honestly all I did was put gas in it. He said it sat behind his house for 5 years. So I fill the tank up and pulled it 2 times and it fired right up. So he said I could have it. I got it home and changed the oil, spark plug, and air filters. And I know I shouldn't be mowing this much grass with a push mower, but I do because I need the exercise haha. So the property is 5 acres andi used it all last year (2011) with it starting on the first pull everytime. I could go outside in the middle of winter and pull it once and it would start. But this year it started acting up . It starts on the first pull when the motor is cold, but once you get the engine warmed up, and stop for 25 minutes, I will pull and pull 15-20 times for it to start. After it sits there and cools for a few hours, it will start right up. Any ideas what this could be???

Look into the choke mechanics if a Briggs. The thermostat behind the muffler could be bad or the swinging parts sticking on shaft, springs broken or unhooked, debris built up on springs and parts etc.

possum said:

Look into the choke mechanics if a Briggs. The thermostat behind the muffler could be bad or the swinging parts sticking on shaft, springs broken or unhooked, debris built up on springs and parts etc.

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I just removed the muffler earlier today, and that thing seemed to move freely and before I tore it down I put 3 in 1 oil on everything and was ok. Btw would loss of compression cause this to happen bcause I removed the head and found a torn head gasket?!??!!?

Does it shut off after warming up ? . If you didnt stop would it stay running for a hr straight ? . I had a customer with a js20 and his would run for 20-30 minutes and shut off and need to cool down and it ended up being the valves.

jetrail said:

Does it shut off after warming up ? . If you didnt stop would it stay running for a hr straight ? . I had a customer with a js20 and his would run for 20-30 minutes and shut off and need to cool down and it ended up being the valves.

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Yeah it will Stay running all day long if I keep it running. It will start back up right after I cut it off and fill the tank with gas, but once you let it sit for 10-20 minutes and try to pull it, it just wont start up.

fix the head gasket and it sounds to me like it could be flooding, it sits a little long and fills with fuel, seeping through needle slightly maybe. put a shut off valve on it, when you stop to take a break turn the fuel off, see what happens when you come back to start it.

twinfords said:

fix the head gasket and it sounds to me like it could be flooding, it sits a little long and fills with fuel, seeping through needle slightly maybe. put a shut off valve on it, when you stop to take a break turn the fuel off, see what happens when you come back to start it.

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Alright I will try that, and when you said something about the valves causing that to happen, if that's the problem, how would I fix it?

i did not say fix the valves, i said install a fuel shut off valve, if it is OHV they could need adjustment. you will need to find specs on what they are supposed to be set at. check them out when you have the head off to fix the gasket etc.

twinfords said:

i did not say fix the valves, i said install a fuel shut off valve, if it is OHV they could need adjustment. you will need to find specs on what they are supposed to be set at. check them out when you have the head off to fix the gasket etc.

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Ok I replaced the head gasket, put on a shut off valve, rebuild the carb, and oil the autochoke and I mowed for about an hour, stopped for a 15 minute break, same d*mn thing, I pulled five or six time and it started. When I pull it, I sounded like it was popping in the carb. And it does actually feel like it it turns over real easy when I pull it too.

check compression, sounds like it may be low. or timing may be off slightly. check shear pin in flywheel.

twinfords said:

check compression, sounds like it may be low. or timing may be off slightly. check shear pin in flywheel.

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I don't have a compression tester, could I just get one at a hardware store?

Autozone might sell them but they are cheaper at harbor freight tools . Is it getting good spark wfter sitting ??? .

jetrail said:

Autozone might sell them but they are cheaper at harbor freight tools . Is it getting good spark wfter sitting ??? .

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Yes its getring good spark after sitting

chevyman984 said:

Ok I replaced the head gasket, put on a shut off valve, rebuild the carb, and oil the autochoke and I mowed for about an hour, stopped for a 15 minute break, same d*mn thing, I pulled five or six time and it started. When I pull it, I sounded like it was popping in the carb. And it does actually feel like it it turns over real easy when I pull it too.

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I would go for a compression test, you may find that the intake valve is a little open when hot, being maybe too tight or just not seating, this will give you (popping back in the carb and also bad starting)
1 Go for compression test, remember to do it when the engine will not start, (HOT) if that is low.
2 Look at the valve (tappet clearance) if o.k make sure they're are seating properly.

Hi everybody, I'm so sorry it took me so long to get back up on here, we had a really bad storm here in nelson county which knocked out power for 5 days with no air conditioning. And then when the power did come back on, the phones were down and internet too for several days, and also dealing with the insurance that wont pay for a big freaking oak tree that fell over and smashed my 1999 suburban. So yeah so sorry!!!! And thanks for everybodys help!

Thats ok, little old Johnny Deere can wait, you need the time to get you're normal life into gear, come back when you ready and let us know if you did get the JS20 going. sorry to hear about the bad new's.:frown:

Hi engineman!!! I'm back up on here. Thanks for everything!! How have you been?

Fine thank you, any news on the Johnny Deere...?

Umm not really. I bought the brggs and stratton maintenance minder, which was probably the worst 30 bucks I've spent in my entire life. And I'm getting ready to give it a complete overhaul/ tune up.I'm gonna change the oil and air filter and precleaner, spark plug, sharpen blade again, and I broke the gas cap on it, so I'm gonna get the frest start cap that comes with 2 cartridges of fresh start fuel stabilizer. Idk if that's why its not starting or not. Ive just been having to pull the cord extra extra hard and it wll start on the first pull. But that about yanks my arm off lol. So if it still does it, ill check compression and all so if that's the problem, ill have to replace the rings. I know it has nothing to do with like the fuel because I spray a shot of starting fluid in it and it still wont start. I know I mentioned the fresh start fuel stabilizer up there, but ill try it and see anyway. Either way ill do it because it would probably be good for it. So that's all the news I've got so far. Actually tomorrow when I get my check I'm gonna ride on over to homedepot and lowes and maybe walmart to get everything for it.

Well you come back and let us know how you do, the only thing I will say is, just take you're time and look things over and do part by part, am sure you will win in the end, in the mean time all the best.

chevyman984 said:

Ok I replaced the head gasket, put on a shut off valve, rebuild the carb, and oil the autochoke and I mowed for about an hour, stopped for a 15 minute break, same d*mn thing, I pulled five or six time and it started. When I pull it, I sounded like it was popping in the carb. And it does actually feel like it it turns over real easy when I pull it too.

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You have touched on it a few times "when i pul it it turns over easely" clearly compression lost and be hard to start. There is more methods to check like removing the sparkplug squirting a spoonful of fuel/oil mixture replace the sparkplug and start it. It is clear that compression is your problem. You are mowing a large area for the mower size it will need good maintanance

Good luck

PJ said:

You have touched on it a few times "when i pul it it turns over easely" clearly compression lost and be hard to start. There is more methods to check like removing the sparkplug squirting a spoonful of fuel/oil mixture replace the sparkplug and start it. It is clear that compression is your problem. You are mowing a large area for the mower size it will need good maintanance

Good luck

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I've always give it good maintenance. If something wasn't kept up, it wasn't me, it was jackleg that. I've got it from. When I got the dern thing the oil was thick as crap. Ill get a tester and check compression

EngineMan said:

Well you come back and let us know how you do, the only thing I will say is, just take you're time and look things over and do part by part, am sure you will win in the end, in the mean time all the best.

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Thanks engineman. I just got back from town and I got everything. Believe it or not I couldn't even find a air filter or precleaner. I replaced them both at the beginning of 2012 mowing season so I might be able to get by with not getting them quite yet.

Ok finnaly found a compression tester!!!!! It is 82 psi cold, and 46 after running an hour. I'm assuming 46 is low???

chevyman984 said:

Ok finnaly found a compression tester!!!!! It is 82 psi cold, and 46 after running an hour. I'm assuming 46 is low???

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46 yes very low even hot, cold should be up at around 100psi, what engine is it. not sure if you post it up I did have a look just didn't find it if you did.

Its either the 675 series briggs and stratton or the 6.75 horspower briggs and stratton.

If its a briggs they don't give you compression readings, but this may help you pin point the problem.

Check Compression
Use Leakdown Tester #19545 to check the sealing capabilities of the compression components.
Follow the instructions provided with the tester to perform the leakdown test.
NOTE: Any air leaks at the connections or fittings of the tester will affect the accuracy of the test.
Listen for air leaking from the cylinder head gasket, carburetor, exhaust system, and the crankcase breather tube.
Air flowing between the cylinder and cylinder head indicates that the cylinder head gasket is leaking.
Air flowing from the carburetor indicates air is leaking past the intake valve and seat.
Air flowing from the exhaust system indicates air is leaking past the exhaust valve and seat.
Air flowing from the crankcase breather tube or high oil fill dipstick tube indicates air is leaking past the piston rings.
Possible Causes for Poor Compression:
Loose cylinder head bolts
Blown head gasket
Burned valves, valve seats and/or loose valve seats
Insufficient tappet clearance
Warped cylinder head
Warped valve stems
Worn bore and/or rings
Broken connecting rod

I know the cylinder walls are worn because when I had the head off to replace the gasket, it was kinda dark looking and had no cross hatching left at all, and just got through adjusting the rpms. And I have a question enginman, when you hit thick grass, and the engine bogga down, shouldn't the governer pick the rpms back up, because it bogga down in the slightest bit of grass, a.d if I keep the mower mowing through the grass, the engine stays "bogged down" it does t pick itself back up.

Yes the governer should pick it up but engine has to be near 100% other things how come into play...! check the links and make sure the governer is working, check also the valves one or maybe two are staying open a little and that would give less compression, you never know. do other test this time with a little oil in cylinder if you get a higher reading its rings, and if you don't can be valves/head gasket etc.

Well I assume the governer works because it mowes, and never have any problems over revving. I will try oil in the cylinder in a minute

Alright oil in cylinder is 93-95 cold

That shows it could well be the rings.

EngineMan said:

That shows it could well be the rings.

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oh my goodness it's been so long!! I have forgotten about this forum!! How is everybody???? So glad to be back

Did you fix the problem...?

chevyman984 said:

I got a lawnmower from my friend, he said it wouldn't run. But honestly all I did was put gas in it. He said it sat behind his house for 5 years. So I fill the tank up and pulled it 2 times and it fired right up. So he said I could have it. I got it home and changed the oil, spark plug, and air filters. And I know I shouldn't be mowing this much grass with a push mower, but I do because I need the exercise haha. So the property is 5 acres andi used it all last year (2011) with it starting on the first pull everytime. I could go outside in the middle of winter and pull it once and it would start. But this year it started acting up . It starts on the first pull when the motor is cold, but once you get the engine warmed up, and stop for 25 minutes, I will pull and pull 15-20 times for it to start. After it sits there and cools for a few hours, it will start right up. Any ideas what this could be???

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By the sound of it the mower has been working hard since you got it. Do compression test. Two reasons, 1)the valves could be worn and not sealing properly 2) The rings could be worn. Now if the compression is low put about a table spoon full of clean engine oil trough the spark plug hole repeat the compression test, if the compresion is now better the rings is the problem if not the valve clearance is your problem.

All the best

PJ

EngineMan said:

Did you fix the problem...?

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well it seems as if it fixed itself. Runs fine now. Although I changed to a thicker oil.

PJ said:

By the sound of it the mower has been working hard since you got it. Do compression test. Two reasons, 1)the valves could be worn and not sealing properly 2) The rings could be worn. Now if the compression is low put about a table spoon full of clean engine oil trough the spark plug hole repeat the compression test, if the compresion is now better the rings is the problem if not the valve clearance is your problem.

All the best

PJ

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Yes it has worked hard. Been a good old lawnmower. And boy I can't wait until my grass starts growing. I love mowing!!!!!!