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6.75 B&S gold

#1

M

markslawnservice@hotmail.

This mower starts and runs when cold. After its warmed up it will sputter and almost backfire and stall. When you go to restart it it will idle real low for 20 seconds then stall. When it cools off it will start and run good again for 15 minutes.
I have changed the gas, gas line, carb, spark plug, manifold, coil and flywheel. It still does it. Head gasket is probably the next step unless somebody knows anything else to check. Thanks for the help.


#2

Scrubcadet10

Scrubcadet10

I think I know what engine you have, but supply us with the model numbers of the engine.
could be the valves are out of adjustment


#3

B

bertsmobile1

Does it blow black smoke when it is playing up ?
The engines with auto choke seem to give a lot of problems .


#4

S

Sabres321

Have you tried changing your gas cap? Some of those caps have a metal thing on the inside of it (the gas cap) and they can fall into the tank. Check for that if you haven’t.


#5

M

markslawnservice@hotmail.

bertsmobile1 said:
Does it blow black smoke when it is playing up ?
The engines with auto choke seem to give a lot of problems .
Click to expand...
No smoke at all, auto choke works fine.


#6

M

markslawnservice@hotmail.

Scrubcadet10 said:
I think I know what engine you have, but supply us with the model numbers of the engine.
could be the valves are out of adjustment
Click to expand...
I'll get that for you, thanks. Didn't,know you could adjust the valves?


#7

Scrubcadet10

Scrubcadet10

On flat heads it's a little more "intensive" as you have to grind off a LITTLE on the end of the valve to open the clearance back up.
But first i would check on what Sabres321 said, and try running it with the gas cap loose so the tank can vent properly. Or when it starts to act up quickly loosen the gas cap and wait to see if it returns normal/.


#8

M

markslawnservice@hotmail.

Sabres321 said:
Have you tried changing your gas cap? Some of those caps have a metal thing on the inside of it (the gas cap) and they can fall into the tank. Check for that if you haven’t.
Click to expand...
Yes I have. Sorry I forgot to mention that.


#9

M

markslawnservice@hotmail.

Scrubcadet10 said:
On flat heads it's a little more "intensive" as you have to grind off a LITTLE on the end of the valve to open the clearance back up.
But first i would check on what Sabres321 said, and try running it with the gas cap loose so the tank can vent properly. Or when it starts to act up quickly loosen the gas cap and wait to see if it returns normal/.
Click to expand...
I have don that numerous times.


#10

M

markslawnservice@hotmail.

Scrubcadet10 said:
I think I know what engine you have, but supply us with the model numbers of the engine.
could be the valves are out of adjustment
Click to expand...
126M02 1525 F1


#11

Scrubcadet10

Scrubcadet10

two versions of carbs were used on that model, Primer and Autochoke.. Do you have the little red bulb you push on the front of the mower?
First we probably ought to rule out, or find out, if it's a fuel issue.
when it dies and you start it back up, and it's idling real low, i would look and see what position the throttle is in, and try to manual change the RPM by adding tension to governor spring or opening the throttle by hand on the carburetor.
if it seems to run better with throttle wide open (more fuel can be drawn in) i would suspect a fuel delivery issue. if runs worse or just dies when you open the throttle, it may be the valve lash is too tight, and then when they get hot and expand there is very little to no clearance and they may not open at the precise time. i think the lash specs are 005" to 007" intake and 007" to 009" exhaust.


#12

M

markslawnservice@hotmail.

Scrubcadet10 said:
two versions of carbs were used on that model, Primer and Autochoke.. Do you have the little red bulb you push on the front of the mower?
First we probably ought to rule out, or find out, if it's a fuel issue.
when it dies and you start it back up, and it's idling real low, i would look and see what position the throttle is in, and try to manual change the RPM by adding tension to governor spring or opening the throttle by hand on the carburetor.
if it seems to run better with throttle wide open (more fuel can be drawn in) i would suspect a fuel delivery issue. if runs worse or just dies when you open the throttle, it may be the valve lash is too tight, and then when they get hot and expand there is very little to no clearance and they may not open at the precise time. i think the lash specs are 005" to 007" intake and 007" to 009" exhaust.
Click to expand...
I will have to Google how to adjust valve lash. I will try that with the throttle lever. Thanks.


#13

M

markslawnservice@hotmail.

Scrubcadet10 said:
two versions of carbs were used on that model, Primer and Autochoke.. Do you have the little red bulb you push on the front of the mower?
First we probably ought to rule out, or find out, if it's a fuel issue.
when it dies and you start it back up, and it's idling real low, i would look and see what position the throttle is in, and try to manual change the RPM by adding tension to governor spring or opening the throttle by hand on the carburetor.
if it seems to run better with throttle wide open (more fuel can be drawn in) i would suspect a fuel delivery issue. if runs worse or just dies when you open the throttle, it may be the valve lash is too tight, and then when they get hot and expand there is very little to no clearance and they may not open at the precise time. i think the lash specs are 005" to 007" intake and 007" to 009" exhaust.
Click to expand...
Mine is auto-choke.


#14

M

markslawnservice@hotmail.

Scrubcadet10 said:
I think I know what engine you have, but supply us with the model numbers of the engine.
could be the valves are out of adjustment
Click to expand...
126M02 1525 F1


#15

Scrubcadet10

Scrubcadet10

Now that we know its an auto choke, there could very well be an issue with that system.


#16

M

markslawnservice@hotmail.

Scrubcadet10 said:
I think I know what engine you have, but supply us with the model numbers of the engine.
could be the valves are out of adjustment
Click to expand...
126M02 1525 F1


#17

M

markslawnservice@hotmail.

Scrubcadet10 said:
Now that we know its an auto choke, there could very well be an issue with that system.
Click to expand...
It seems to close when cold and open when hot.


#18

Scrubcadet10

Scrubcadet10

That's how it's supposed to be, when the mower is running and starts acting up, look to see what position the choke is in, you can let it run without the airfilter, or leave the air filter cover on loose so you can take it off quickly and you should be able to see the choke butterfly in the carburetor. should be open. all the way.
But since you said it doesn't blow any black smoke when its acting up, that's probably not the problem.


#19

M

markslawnservice@hotmail.

I understand. I'll check later, thanks.


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