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Won't start when hot.

#1

S

Sapman

I have a Craftsman riding mower, about 10 years old, with a 19 HP B&S engine. It starts and runs fine, but if I shut it down for more than about 2 minutes, it will not start again until it has significantly cooled down. It turns over and seems to have plenty of spark, but will not fire up. Any ideas what the problem may be, or how to further diagnose it?


#2

L

lawngeorge

Sapman said:
I have a Craftsman riding mower, about 10 years old, with a 19 HP B&S engine. It starts and runs fine, but if I shut it down for more than about 2 minutes, it will not start again until it has significantly cooled down. It turns over and seems to have plenty of spark, but will not fire up. Any ideas what the problem may be, or how to further diagnose it?
Click to expand...

hi sapman i have a similar problem,with my briggs mine is 98model 17.5 twin oppose cilinders


#3

L

lawngeorge

lawngeorge said:
hi sapman i have a similar problem,with my briggs mine is 98model 17.5 twin oppose cilinders
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let me tell what ive done to it,replaced the coil rebuilt the carb again,i rebuilt it last year and still does the same thing.cranks and runs greAt when cold butad soon ad it get alittle warm or hot and you shut it off ,game is over till the darn thing cools off


#4

L

lawngeorge

lawngeorge said:
let me tell what ive done to it,replaced the coil rebuilt the carb again,i rebuilt it last year and still does the same thing.cranks and runs greAt when cold butad soon ad it get alittle warm or hot and you shut it off ,game is over till the darn thing cools off
Click to expand...

hey sapman whats the engine model number??


#5

T

Tinkerer200

I suggest you shut off the gas before stopping the engine. If it has an inline shutoff, use it if not, clamp the gas line before shutting off and see if this helps. IF it does, add an inline gas shut off and use it.

Walt Conner


#6

EngineMan

EngineMan

Check compression when hot could be a valve, or starvation of fuel. or head gasket.


#7

B

bertsmobile1

EngineMan said:
Check compression when hot could be a valve, or starvation of fuel. or head gasket.
Click to expand...

or a cracked head


#8

L

lawngeorge

Tinkerer200 said:
I suggest you shut off the gas before stopping the engine. If it has an inline shutoff, use it if not, clamp the gas line before shutting off and see if this helps. IF it does, add an inline gas shut off and use it.

Walt Conner
Click to expand...

I already put an inline shut off valve,but it didnt help. I also have a spark tester the one that glows ,it is firing on both cylinders but only when it cools off it actually starts.I read on a few threads about the float needle not closing correctly and over flowing the bowl, and flooding the engine .But in my case the plugs are not wet at all.Now moving to the coil i order one online, but this coil fires but it wont start the engine even when cold. My engine is 2 cylinder opposed engine. So i used the old coil and it fires and starts the engine when cold


#9

L

lawngeorge

bertsmobile1 said:
or a cracked head
Click to expand...
engine man, thats what i doing later on when i get home check for compression im going to start cold then im checking after it gets hot and see what it does.....


#10

L

lawngeorge

lawngeorge said:
I already put an inline shut off valve,but it didnt help. I also have a spark tester the one that glows ,it is firing on both cylinders but only when it cools off it actually starts.I read on a few threads about the float needle not closing correctly and over flowing the bowl, and flooding the engine .But in my case the plugs are not wet at all.Now moving to the coil i order one online, but this coil fires but it wont start the engine even when cold. My engine is 2 cylinder opposed engine. So i used the old coil and it fires and starts the engine when cold
Click to expand...

tinkerer thanks alot for inline shut off valve, tip


#11

S

Sapman

So, same thing today. Mower started and ran fine, but as soon as I stopped to empty the leaves out of the baskets, it wouldn't start. Yesterday I pulled a plug and had my wife turn it over, and I saw plenty of spark. So tonight I pulled the air filter off and dumped a little gas into the carb, but still nothing! So, I'm perplexed. Small engines are not rocket science; usually spark plus fuel equals at least some kind of run. Would a lack of compression lead to no firing at all?


#12

T

Tinkerer200

lawngeorge said:
tinkerer thanks alot for inline shut off valve, tip
Click to expand...

When installing the aftermarket coil, are you sure you installed it correctly? Plug leads exit coil on side opposite the spark plugs then lope under the coil and go back the other direction to plugs.

Walt Conner


#13

L

lawngeorge

Tinkerer200 said:
When installing the aftermarket coil, are you sure you installed it correctly? Plug leads exit coil on side opposite the spark plugs then lope under the coil and go back the other direction to plugs.

Walt Conner
Click to expand...

yes, i connected the coil the way it is supposed to be,the left side of plug cable goes to the right sparkplug and vice versa. However i still havent check compression cold and hot i got home late from work i dint feel like messing with it.but tomorrow i cant wait to get my hands on it, believe me. This model is a 42a707 2653e1 it runs quite well and cut good Thats why i want to get it run right. I didn't mentioned that this machine doesn't cut off at all,you can go i guess for hours mowing, the most i've gone is about 1hour but as soon as i turn it off, game is over will not cranks till cool,in fact a friend of mine told me this ,that a few years back his brother had a similar machine to mine. the problem with that one was a sticking exaust valve when ever it got hot the valve stayed open thus causing the engine not to start, but it would still fire.i wonder if that what's wrong with mine.tinkerer any advice will be greatly appreciated.
thanks


#14

L

lawngeorge

Sapman said:
So, same thing today. Mower started and ran fine, but as soon as I stopped to empty the leaves out of the baskets, it wouldn't start. Yesterday I pulled a plug and had my wife turn it over, and I saw plenty of spark. So tonight I pulled the air filter off and dumped a little gas into the carb, but still nothing! So, I'm perplexed. Small engines are not rocket science; usually spark plus fuel equals at least some kind of run. Would a lack of compression lead to no firing at all?
Click to expand...

sapman im in the same situation as you are im very perplexed, tomorrow im doing a compression check and according to the results, i might take the cylinder heads apart. Iwill post something tomorrow .take care


#15

Carscw

Carscw

If the coil you got is a after market clone. Then it does not install the same. Try flipping it over.

These engine love to do this.
Why I do not know and have not found anyone that knows.

This problem is why I joined this group years ago.


#16

L

lawngeorge

Carscw said:
If the coil you got is a after market clone. Then it does not install the same. Try flipping it over.

These engine love to do this.
Why I do not know and have not found anyone that knows.

This problem is why I joined this group years ago.
Click to expand...

uuhhh, I will try this today....if it doesnt starts the engine ,ill return it .the old coil works fine when cold. Thanks carscw


#17

T

Tinkerer200

As for cracked head or stuck valve, note that these engines will start and run quit happily on one cylinder. The examples I have found of this have been because gas leaked into cylinders after shutting down resulting in flooding which is the reason for shutting the gas off a few seconds before stopping the engine OR a failing coil "Heat Soaking" when engine is turned off.

Walt Conner


#18

S

Sapman

Is there a way to test the coil before replacing it? Is it as simple as checking for spark? I would think that a lack of compression problem would result in poor performance, but when it is running, it seems to have plenty of power. It does go through some oil. The plug color looks good; not oily or wet.


#19

RoperGuy

RoperGuy

Shot In the dark but remove your air filter and manually choke with your hand. By the sounds, spark isent your issue, other wise you would smell fuel on the plugs after removing. Should check your compression, even roll over by hand if you have to, before start and and after hot.


#20

EngineMan

EngineMan

There should be a fuel SOLENOID fitted if so check it.

Begin troubleshooting the solenoid by checking for battery voltage at the spade connector (with the key switch in the “start” as well as the “run” position). The next check is to listen at the bowl of the carburetor for a distinct click when the ignition switch is turned to the on position. If a distinct click is not heard, remove the solenoid for further testing.
To test the solenoid itself, attach one pole of a 9 volt transistor radio battery to the spade terminal and the other pole to the solenoid case or black ground wire
if so equipped. A sharp distinct movement of the plunger should be seen.
A poor solenoid ground connection or dirty/stale fuel are common causes of anti-afterfire solenoid problems.


#21

Carscw

Carscw

Will not be a anti backfire ( shut off )
Solenoid on this engine.


#22

EngineMan

EngineMan

Carscw said:
Will not be a anti backfire ( shut off )
Solenoid on this engine.
Click to expand...

Are you sure its showing one in the manual for that engine number.


#23

Carscw

Carscw

EngineMan said:
Are you sure its showing one in the manual for that engine number.
Click to expand...

Assuming we are still talking about the opposed twin.
Have never seen one on them.


#24

EngineMan

EngineMan

42a707....

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#25

L

lawngeorge

lawngeorge said:
hey sapman whats the engine model number??
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hi guys im back after a few months


#26

T

Tinkerer200

I have literally had dozens of these engines and only recall seeing one with a carb solenoid towards the end of the run on them. IF there is one it will be sticking up at an angle on the lower right hand side of the carb when facing the carb side of the engine.

Walt Conner


#27

troy-built

troy-built

lawngeorge said:
yes, i connected the coil the way it is supposed to be,the left side of plug cable goes to the right sparkplug and vice versa. However i still havent check compression cold and hot i got home late from work i dint feel like messing with it.but tomorrow i cant wait to get my hands on it, believe me. This model is a 42a707 2653e1 it runs quite well and cut good Thats why i want to get it run right. I didn't mentioned that this machine doesn't cut off at all,you can go i guess for hours mowing, the most i've gone is about 1hour but as soon as i turn it off, game is over will not cranks till cool,in fact a friend of mine told me this ,that a few years back his brother had a similar machine to mine. the problem with that one was a sticking exaust valve when ever it got hot the valve stayed open thus causing the engine not to start, but it would still fire.i wonder if that what's wrong with mine.tinkerer any advice will be greatly appreciated.
thanks
Click to expand...
It sure would have been nice if he had posted what the problem was if he fixed it. That's exactly what my mower is doing and the exact same motor.


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