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Craftsman Lown Mower 24 hp Briggs Stratton Engine, Model 917.288560

#1

M

MaryAnn Cafaro

When engine runs, it surges in low and high rpm. We cleaned the carburetor, the fuel filter and set the valves. It starts up very easily but still surges a little and appears to be running lean. I do not want to cut the lawn for fear of running it hot and causing an overheat. Thank you for your help. MaryAnn and Frank


#2

B

bertsmobile1

MaryAnn Cafaro said:
When engine runs, it surges in low and high rpm. We cleaned the carburetor, the fuel filter and set the valves. It starts up very easily but still surges a little and appears to be running lean. I do not want to cut the lawn for fear of running it hot and causing an overheat. Thank you for your help. MaryAnn and Frank
Click to expand...

By cleaning the carb do you mean pulling it off completely removing all the jets and chacking all of the fine holes for blockages ?
If that answer is yes then get some WD 40 or similar IN A TRIGGER PACK ( yes I was shouting ) and spray around the carb when the engine is running paying particular attention to the inlet manifold.
If you get a sudden change then air is leaking in at that point and you need to replace whatever is there ( gasket O ring etc).


#3

M

MaryAnn Cafaro

bertsmobile1 said:
By cleaning the carb do you mean pulling it off completely removing all the jets and chacking all of the fine holes for blockages ?
If that answer is yes then get some WD 40 or similar IN A TRIGGER PACK ( yes I was shouting ) and spray around the carb when the engine is running paying particular attention to the inlet manifold.
If you get a sudden change then air is leaking in at that point and you need to replace whatever is there ( gasket O ring etc).
Click to expand...

Thank you for your answer --- I did not use WD40, but used AMSOIL MP which is very similar and did not have any change in operation. I will try it again with the WD40,
We did strip down the complete carburetor and cleaned out all the passages and jets. Appreciate your info and will get back with you. thanks again


#4

B

bertsmobile1

MaryAnn Cafaro said:
Thank you for your answer --- I did not use WD40, but used AMSOIL MP which is very similar and did not have any change in operation. I will try it again with the WD40,
We did strip down the complete carburetor and cleaned out all the passages and jets. Appreciate your info and will get back with you. thanks again
Click to expand...

No need to try again, any fluid will do, all you are trying to do is let it get sucked into the engine i there is an air leak in there which is why you were told to spray it around the carb/ engine joint.
Trigger pack is important to get a flood of fluid there and to prevent the propellant found in spray packs catching fire. Some even use water but that becomes messy if too much gets sucked into the engine.

Hunting is running lean and running lean is either not enough fuel or too much air entering after the carb had dispensed the fuel.

Not enough fuel is either not enough flow to the carb
or float height too low
Or fuel jets blocked

So it is back to the beginning & try again.


#5

M

MaryAnn Cafaro

bertsmobile1 said:
No need to try again, any fluid will do, all you are trying to do is let it get sucked into the engine i there is an air leak in there which is why you were told to spray it around the carb/ engine joint.
Trigger pack is important to get a flood of fluid there and to prevent the propellant found in spray packs catching fire. Some even use water but that becomes messy if too much gets sucked into the engine.

Hunting is running lean and running lean is either not enough fuel or too much air entering after the carb had dispensed the fuel.

Not enough fuel is either not enough flow to the carb
or float height too low
Or fuel jets blocked

So it is back to the beginning & try again.
Click to expand...

HI BERTSMOBILE: when I get it running - will let you know...thanks again!!!


#6

S

supertech

you can slowly cup your hand over the top of carb while running at idle. If the idle increase and the engine smooths out then theres a vacumm leak.


#7

M

motoman

Suspicion of lean running... did you look at the porcelin color on the plugs? Perhaps the condition has not persisted long enough to burn off the normal tan to a whitish or lighter color. Check. It could be another clue. Also did power trail off a little which would be expected under load such as hills, PTO on, baskets full ?


#8

M

MaryAnn Cafaro

supertech said:
you can slowly cup your hand over the top of carb while running at idle. If the idle increase and the engine smooths out then theres a vacumm leak.
Click to expand...

Hello: Running at idle we closed off 80% of the intake and it made no difference. At 90% it ran smooth indicating a manifold leak. Have to table this project for awhile When we get back to it we will let you know the outcome. Thank you very much for your time and info. :smile:


#9

M

MaryAnn Cafaro

motoman said:
Suspicion of lean running... did you look at the porcelin color on the plugs? Perhaps the condition has not persisted long enough to burn off the normal tan to a whitish or lighter color. Check. It could be another clue. Also did power trail off a little which would be expected under load such as hills, PTO on, baskets full ?
Click to expand...

Hello: We checked the spark plugs and they have a normal burning indication. Thanks for your time and info.....Have to table the project for awhile...Will let you
know when I get back to it.......Frank and MaryAnn:smile:


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