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Dies After 45 Minutes Running
#1
F
Fnu Lnu
F
Fnu Lnu
Briggs and Stratton Engine 12H802-2677B1 Engine on a lawnmower starts and runs. However, after about 45 minutes of running full speed, depending upon the outside temperature, it will die and not start until it is full cooled off.
I have;
• de-carbon the head and top of the piston
• buffed the rust & corrosion off of the armature / magneto and the flywheel; gapped & reinstalled
But it ran the same.
I suspect a weak armature / magneto because the engine is 24 years old.
Am I heading in the right direction?
I have;
• de-carbon the head and top of the piston
• buffed the rust & corrosion off of the armature / magneto and the flywheel; gapped & reinstalled
But it ran the same.
I suspect a weak armature / magneto because the engine is 24 years old.
Am I heading in the right direction?
#2
B
Bertrrr
B
Bertrrr
Make sue it's not fuel related first , your tank vent possibly is plugged off , then check for fire if / when it happens again , still have fire , it's fuel related In my opinion
#3
F
Fnu Lnu
F
Fnu Lnu
I really do not believe that the issue is fuel related because the carburetor is a new OEM Briggs & Stratton, the fuel cap is clean, the fuel tank is clean and rust free (I only use real gasoline, not car gas), the in-line fuel filter is new, the air filter is new, and the spark plug is new.
The issue seems to be heat related because while mowing 1/4 acre, full throttle, during the heat of the day after about 3/4 hour or so it will die and cannot be restarted for about an hour or more of letting it cool off in the shade.
The mower was purchased new back in 2000, so it is 24 years old. However I stopped using this mower (self-propelled Snapper) back in 2017 when I bought a lawn tractor. Then last year I broke a mandrel (hidden rocks) and punctured too many holes in one of the steering tires (hidden thorns) while helping my elderly neighbor by mowing their property (no good deed shall go unpunished). So while waiting for the new parts to come in I decided to use the 23 year old Snapper on our property. That was when I experienced the "dies when hot" issue, which is why I am questioning about the possibility of the armature / magneto being weak.
The issue seems to be heat related because while mowing 1/4 acre, full throttle, during the heat of the day after about 3/4 hour or so it will die and cannot be restarted for about an hour or more of letting it cool off in the shade.
The mower was purchased new back in 2000, so it is 24 years old. However I stopped using this mower (self-propelled Snapper) back in 2017 when I bought a lawn tractor. Then last year I broke a mandrel (hidden rocks) and punctured too many holes in one of the steering tires (hidden thorns) while helping my elderly neighbor by mowing their property (no good deed shall go unpunished). So while waiting for the new parts to come in I decided to use the 23 year old Snapper on our property. That was when I experienced the "dies when hot" issue, which is why I am questioning about the possibility of the armature / magneto being weak.
#4
B
Bertrrr
B
Bertrrr
Coils can stop working after getting hot ,sorta rare but happens sometime , when it happens again , see if there is still a spark at the plug , if not it's probably the coil
#5
G
GearHead36
G
GearHead36
Unless you took it apart, the vent could still be plugged. Next time it does it, remove the fuel cap, and see if that fixes it.the fuel cap is clean
#6
D
DaveTN
D
DaveTN
Just curious what color spark is at beginning cold and when it’s hot and quits. Does
it start to cut out and miss or lose power and die all at once?
it start to cut out and miss or lose power and die all at once?
#7
S
Skippydiesel
S
Skippydiesel
".........the fuel tank is clean and rust free (I only use real gasoline, not car gas)"
All metal fuel tanks can/will rust.
All fuel tanks "sweat" ie condensation develops . This is especially so in climates that have a wide daily temperature range, at certain times of the year. The condensat collects in the bottom of the tank. Plastic tanks will not rust of course however metal ones will - it may take along time but nature will take its course.
The only long term preventions are:
All metal fuel tanks can/will rust.
All fuel tanks "sweat" ie condensation develops . This is especially so in climates that have a wide daily temperature range, at certain times of the year. The condensat collects in the bottom of the tank. Plastic tanks will not rust of course however metal ones will - it may take along time but nature will take its course.
The only long term preventions are:
- Drain tank regularly (at least once per season)
- Keep tanks a minimum of 75% full
#8
F
Fnu Lnu
F
Fnu Lnu
SkippyDiesel,
I really should have said that the fuel tank is plastic. I misspoke. Also, as to your comment; "Water may be worse with ethanol blends"; thus the reason that I only use real gasoline.
At the local small town source for "real gasoline"; one day last year (2023) I was buying more fuel because I had finally used up the absolute last of the fuel that I bought back in 2021. I asked the owner how long this gasoline will last, explaining that what I was currently burning (remember that this was last year) was two years old. He asked another customer, an older gentleman; "You know better than I do, how long does this gasoline last?". The old man answered; "At least seven (7) years.".
That is why anyone I am visiting with and the conversation gets around to small engines, I highly recommend that they avoid using automobile gas and then tell them of a few places where they can get the real gasoline.
Thank You for reminding me about metal fuel tanks. Of the 7 or so small engine units that I have, 2 of them have metal fuel tanks. I will be more careful about Winterizing them this year because of your advice.
I really should have said that the fuel tank is plastic. I misspoke. Also, as to your comment; "Water may be worse with ethanol blends"; thus the reason that I only use real gasoline.
At the local small town source for "real gasoline"; one day last year (2023) I was buying more fuel because I had finally used up the absolute last of the fuel that I bought back in 2021. I asked the owner how long this gasoline will last, explaining that what I was currently burning (remember that this was last year) was two years old. He asked another customer, an older gentleman; "You know better than I do, how long does this gasoline last?". The old man answered; "At least seven (7) years.".
That is why anyone I am visiting with and the conversation gets around to small engines, I highly recommend that they avoid using automobile gas and then tell them of a few places where they can get the real gasoline.
Thank You for reminding me about metal fuel tanks. Of the 7 or so small engine units that I have, 2 of them have metal fuel tanks. I will be more careful about Winterizing them this year because of your advice.
#9
F
Fnu Lnu
I have not tested the spark because when it dies I wear myself out pulling the starter rope.
It dies as if it had a "Kill Switch" or an "On / Off Switch" and someone turned the engine Off while I was mowing.
F
Fnu Lnu
Dave,Just curious what color spark is at beginning cold and when it’s hot and quits. Does
it start to cut out and miss or lose power and die all at once?
I have not tested the spark because when it dies I wear myself out pulling the starter rope.
It dies as if it had a "Kill Switch" or an "On / Off Switch" and someone turned the engine Off while I was mowing.
#10
D
DaveTN
orange reddish spark means coil weak and going out. That’s why I asked about color of spark.
D
DaveTN
If you’re getting good bluish white spark at beginning and end the coil should be fine. WeakDave,
I have not tested the spark because when it dies I wear myself out pulling the starter rope.
It dies as if it had a "Kill Switch" or an "On / Off Switch" and someone turned the engine Off while I was mowing.
orange reddish spark means coil weak and going out. That’s why I asked about color of spark.
#11
F
Fnu Lnu
F
Fnu Lnu
Dave,
THAT, is Very Valuable Information.
I am on a project that I need to finish before getting back on the Briggs & Stratton engine. As soon as I can I will test the Spark Color.
Thank You So Much!
THAT, is Very Valuable Information.
I am on a project that I need to finish before getting back on the Briggs & Stratton engine. As soon as I can I will test the Spark Color.
Thank You So Much!
#12
R
Rivets
R
Rivets
Color of the spark makes very little difference, you just need to check to see if you have any spark at all when the unit dies.
#13
Tiger Small Engine
Tiger Small Engine
So does blaming lots of issues on 87 octane 10% ethanol fuel. All my small engines run great on it. The debate continues…Color of the spark makes very little difference, you just need to check to see if you have any spark at all when the unit dies.
#14
F
Fnu Lnu
Some people have explained to me that the 87 Octane 10% Ethanol Fuel left untreated will only last about 6 months. Treated with a fuel stabilizer extends it possibly another 6 months.
Because I have 9 or more small engine machines I store extra gasoline, upwards of 20 gallons or so. Also I have some machines that will not be used for a year or more. One season I was burning 2-year-old untreated gasoline as late as June because the year before was so hot and dry that I did not mow the yard at all.
We live in a small population county in the south central Texas hill country. When I went to the local supplier to refill my cans I asked the owner how long this gasoline will last. The owner, in turn, called to an older man by name who was there and asked him. The old man said that he did not know how long, but he knew it would last at least 7 years. Then someone told of starting a motorcycle on the third kick that had been setting in a barn for 10 to 15 years. The old man who owned it could not remember when it was last used.
I very seriously doubt that 87 Octane 10% Ethanol Fuel would last much more than 9 months left untreated without having some sort of Start / Run issues.
If I offended you with my comment about fuel preference, then I would ask you to accept my apology, that was not my intention.
F
Fnu Lnu
My apologies if I offended you about my preference of fuel type. It is simply that my personal experience with 87 Octane 10% Ethanol Fuel has been that when it is left in the tank too long the fuel sours and starts to smell bad. Also, left in the carburetor too long it gums up. I have had to replace the carburetor on 3 different machines that had been left un-running for about a year with 87 Octane 10% Ethanol Fuel in the carburetor.So does blaming lots of issues on 87 octane 10% ethanol fuel. All my small engines run great on it. The debate continues…
Some people have explained to me that the 87 Octane 10% Ethanol Fuel left untreated will only last about 6 months. Treated with a fuel stabilizer extends it possibly another 6 months.
Because I have 9 or more small engine machines I store extra gasoline, upwards of 20 gallons or so. Also I have some machines that will not be used for a year or more. One season I was burning 2-year-old untreated gasoline as late as June because the year before was so hot and dry that I did not mow the yard at all.
We live in a small population county in the south central Texas hill country. When I went to the local supplier to refill my cans I asked the owner how long this gasoline will last. The owner, in turn, called to an older man by name who was there and asked him. The old man said that he did not know how long, but he knew it would last at least 7 years. Then someone told of starting a motorcycle on the third kick that had been setting in a barn for 10 to 15 years. The old man who owned it could not remember when it was last used.
I very seriously doubt that 87 Octane 10% Ethanol Fuel would last much more than 9 months left untreated without having some sort of Start / Run issues.
If I offended you with my comment about fuel preference, then I would ask you to accept my apology, that was not my intention.
#15
Tiger Small Engine
Tiger Small Engine
No need to apologize whatsoever. Today’s fuels (87 ethanol, 89, 91, 93) are not what they used to be say 20 years ago. Fuel treated with stabilizer (91 no ethanol) will often not last the two years that is claimed to start and run a small engine. I am not a fuel stabilizer fan.I see lots of fuel from customer equipment with water in it. They claim they are running non ethanol fuel. Keep it moving (fresh fuel) is my mindset. If you are not going to use the equipment for extended periods of time, dump or drain it out.My apologies if I offended you about my preference of fuel type. It is simply that my personal experience with 87 Octane 10% Ethanol Fuel has been that when it is left in the tank too long the fuel sours and starts to smell bad. Also, left in the carburetor too long it gums up. I have had to replace the carburetor on 3 different machines that had been left un-running for about a year with 87 Octane 10% Ethanol Fuel in the carburetor.
Some people have explained to me that the 87 Octane 10% Ethanol Fuel left untreated will only last about 6 months. Treated with a fuel stabilizer extends it possibly another 6 months.
Because I have 9 or more small engine machines I store extra gasoline, upwards of 20 gallons or so. Also I have some machines that will not be used for a year or more. One season I was burning 2-year-old untreated gasoline as late as June because the year before was so hot and dry that I did not mow the yard at all.
We live in a small population county in the south central Texas hill country. When I went to the local supplier to refill my cans I asked the owner how long this gasoline will last. The owner, in turn, called to an older man by name who was there and asked him. The old man said that he did not know how long, but he knew it would last at least 7 years. Then someone told of starting a motorcycle on the third kick that had been setting in a barn for 10 to 15 years. The old man who owned it could not remember when it was last used.
I very seriously doubt that 87 Octane 10% Ethanol Fuel would last much more than 9 months left untreated without having some sort of Start / Run issues.
If I offended you with my comment about fuel preference, then I would ask you to accept my apology, that was not my intention.
#16
I
ILENGINE
I
ILENGINE
If the fuel has water in it, at that point it is ethanol free. Because the water has captured the ethanol and removed it from the equation. So their 87 with ethanol is now 85 octane.No need to apologize whatsoever. Today’s fuels (87 ethanol, 89, 91, 93) are not what they used to be say 20 years ago. Fuel treated with stabilizer (91 no ethanol) will often not last the two years that is claimed to start and run a small engine. I am not a fuel stabilizer. I see lots of fuel from customer equipment with water in it. They claim they are running non ethanol fuel. Keep it moving (fresh fuel) is my mindset. If you are not going to use the equipment for extended periods of time, dump or drain it out.
#17
B
bluesky
B
bluesky
I had the same problem as the OP. After cleaning the carburetor several times with no improvement. we found the problem. The fuel filter "in the fuel tank" on the end of the fuel line was pluged. Replacing that filter has solved all the starting/running issues.
We used a stiff wire with the end bent into a hook ( J shape) to grab the fuel line and pull it out through the tank fill hole.
9J
We used a stiff wire with the end bent into a hook ( J shape) to grab the fuel line and pull it out through the tank fill hole.
9J
#18
J
JohnFrancis
J
JohnFrancis
I’ve also found debris stuck in the fuel lines after replacing the fuel filter and removing the cap to check. Once it was dead wasps… Blew out the fuel lines and has been running great for several years.Unless you took it apart, the vent could still be plugged. Next time it does it, remove the fuel cap, and see if that fixes it.
#19
G
Gord Baker
G
Gord Baker
Use a funnel with a fine screen when refueling. Ethanol fuel lasts for about 30 days before degrading. Don't drain out the last dregs from a tank metal or plastic. That is where the Water is.SkippyDiesel,
I really should have said that the fuel tank is plastic. I misspoke. Also, as to your comment; "Water may be worse with ethanol blends"; thus the reason that I only use real gasoline.
At the local small town source for "real gasoline"; one day last year (2023) I was buying more fuel because I had finally used up the absolute last of the fuel that I bought back in 2021. I asked the owner how long this gasoline will last, explaining that what I was currently burning (remember that this was last year) was two years old. He asked another customer, an older gentleman; "You know better than I do, how long does this gasoline last?". The old man answered; "At least seven (7) years.".
That is why anyone I am visiting with and the conversation gets around to small engines, I highly recommend that they avoid using automobile gas and then tell them of a few places where they can get the real gasoline.
Thank You for reminding me about metal fuel tanks. Of the 7 or so small engine units that I have, 2 of them have metal fuel tanks. I will be more careful about Winterizing them this year because of your advice.
#20
Thornback
Thornback
I had the exact same heat problem with my lawn mower. It was a flat head engine, not an OHV. It would run about 20 minutes and then shut off. It would not restart until it cooled off. I was told the valve seats were soft and over the years the valves would hammer the seats letting the valves rest further into the seat thus reducing the valve stem gap. Once the engine heated up the expansion would close the valve gap and then the engine would lose compression because the valves did not seat. I ground about .010 off the end of each valve stem and that cured the problem. When your mower stops you might test the compression to see if that is your problem.
#21
B
Back44L&G
B
Back44L&G
I have used non-ethanol mixed with Sta-BIL at the time of purchase for the past 30 years with no fuel issues. I mix it with an extra measure of the stabilizer for the stated two-year life which lasts about 18 months to turn over my supply. Non-ethanol without any stabilization will not last seven years. That’s wishful thinking as it’s only good for about sixty days. All of my equipment is stored in a utility barn and not left outside in the weather. Since using Sta-Bil, I have not experienced any carburetor problems.".........the fuel tank is clean and rust free (I only use real gasoline, not car gas)"
All metal fuel tanks can/will rust.
All fuel tanks "sweat" ie condensation develops . This is especially so in climates that have a wide daily temperature range, at certain times of the year. The condensat collects in the bottom of the tank. Plastic tanks will not rust of course however metal ones will - it may take along time but nature will take its course.
The only long term preventions are:
Water may be worse with ethanol blends due to the hygroscopic nature of the ethanol.
- Drain tank regularly (at least once per season)
- Keep tanks a minimum of 75% full
#23
C
Catenary Kid
C
Catenary Kid
Many years ago I had a Simplicity mower with the same problem. For years it would run great until it got good and hot (usually about 2 hours, depending on ambient temps) then just quit. Nothing I did would make it run until it cooled down, when it would start and run just fine for exponentially decreasing times until it quit again. I tried everything with no success until a mechanic acquaintance told me it was vapor locking, which I found was indeed the case. I finally solved the problem by trading it in on a new mower.
#24
B
Back44L&G
B
Back44L&G
About six years ago, I had a vapor lock issue with a 2007 Troy-built pressure washer with a Briggs & Stratton 8.75 HP engine. It would run when it was cold but when it ran out of fuel and was refilled, it was always hard to start. I called the local dealer and was advised that B&S had redesigned the gas caps. I ordered new gas caps for all of my B&S engines and haven't had any more issues. Some years ago, Honda had a similar problem with their walk-behind mowers. There are several videos on YouTube on how to retrofit Honda gas caps so they vent better.Many years ago I had a Simplicity mower with the same problem. For years it would run great until it got good and hot (usually about 2 hours, depending on ambient temps) then just quit. Nothing I did would make it run until it cooled down, when it would start and run just fine for exponentially decreasing times until it quit again. I tried everything with no success until a mechanic acquaintance told me it was vapor locking, which I found was indeed the case. I finally solved the problem by trading it in on a new mower.
#25
S
SamB
If your Snapper is an RER, It is worth getting running again.
S
SamB
I am not 100% sure , but Snapper didn't have anything but polyethylene gas tanks, like well....forever.".........the fuel tank is clean and rust free (I only use real gasoline, not car gas)"
All metal fuel tanks can/will rust.
All fuel tanks "sweat" ie condensation develops . This is especially so in climates that have a wide daily temperature range, at certain times of the year. The condensat collects in the bottom of the tank. Plastic tanks will not rust of course however metal ones will - it may take along time but nature will take its course.
The only long term preventions are:
Water may be worse with ethanol blends due to the hygroscopic nature of the ethanol.
- Drain tank regularly (at least once per season)
- Keep tanks a minimum of 75% full
If your Snapper is an RER, It is worth getting running again.
#26
T
TobyU
Secondly, always diagnose a problem before you do anything to it or change any parts.
First thing you should determine when this happens is whether it doesn't have fuel or spark because there's a 99% chance one of those two things is the culprit.
It's actually more like 99.9999%, but occasionally you will find one where when it warms up or when the sunlight gets the handle hot, the kill switch cable moves just enough to tickle the kill switch but like I said it's rare.
So get it hot and wait till it dies and then give it a little bit of gas into the carburetor I pushing the primer bulb if it has one or a little bit of carb cleaner spray in there or dribble a teaspoon of gas into the carb and try it again.
If it runs at all you know it's fuel but my guess is it will not because it sounds like you have a coil on its way out but they typically will not run 45 minutes until they fail.
I run 12 to 18 and that's like clockwork.
Regardless, then pull the plug out and get another used plug or whatever you have or another known good plug and check for spark.
If you don't see a nice snappy spark when someone pulls the rope and you hold the plug and the wire next to the block then you can almost bet it's coil.
But then before you replace that, take the small kill switch wire off the coil and check for spark again because sometimes you have a bare spot on a wire and when things vibrate and get just warm enough it will pinch that wire just enough to kill itself out and then once it cools off it will move a little bit the other way and be okay.
Temperature and vibration do a
weird things.
T
TobyU
Okay, first of all stop taking heads off of engine to decarbonize anything because it's just a waste of time. LolBriggs and Stratton Engine 12H802-2677B1 Engine on a lawnmower starts and runs. However, after about 45 minutes of running full speed, depending upon the outside temperature, it will die and not start until it is full cooled off.
I have;
• de-carbon the head and top of the piston
• buffed the rust & corrosion off of the armature / magneto and the flywheel; gapped & reinstalled
But it ran the same.
I suspect a weak armature / magneto because the engine is 24 years old.
Am I heading in the right direction?
Secondly, always diagnose a problem before you do anything to it or change any parts.
First thing you should determine when this happens is whether it doesn't have fuel or spark because there's a 99% chance one of those two things is the culprit.
It's actually more like 99.9999%, but occasionally you will find one where when it warms up or when the sunlight gets the handle hot, the kill switch cable moves just enough to tickle the kill switch but like I said it's rare.
So get it hot and wait till it dies and then give it a little bit of gas into the carburetor I pushing the primer bulb if it has one or a little bit of carb cleaner spray in there or dribble a teaspoon of gas into the carb and try it again.
If it runs at all you know it's fuel but my guess is it will not because it sounds like you have a coil on its way out but they typically will not run 45 minutes until they fail.
I run 12 to 18 and that's like clockwork.
Regardless, then pull the plug out and get another used plug or whatever you have or another known good plug and check for spark.
If you don't see a nice snappy spark when someone pulls the rope and you hold the plug and the wire next to the block then you can almost bet it's coil.
But then before you replace that, take the small kill switch wire off the coil and check for spark again because sometimes you have a bare spot on a wire and when things vibrate and get just warm enough it will pinch that wire just enough to kill itself out and then once it cools off it will move a little bit the other way and be okay.
Temperature and vibration do a
weird things.