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Stumbling engine.

#1

B

bobbwsny

Hello,

I have a John Deere 14SE walk behind mower from the mid 90's that I acquired a year ago or so. Can't believe how solid this thing is built, but unfortunatly I can't get the engine, a Kawasaki FC150v, running properly. It starts right up, runs great for about 10 minutes, then starts stumbling. The engine seems to be getting too much fuel, or the electrical system is breaking down. I have had the carb off and apart many times, it is clean, even took the carb to a mower repair shop owned by a friend, they took it apart and could fine no problem with it. The carb and choke linkages are adjusted fine, the carb float seems to be working fine, the needle seems to be seating properly. Have tried many different brands and proper new spark plugs with the same results, they all turn black right away. Tested the OHM resistances in the coil, both primary and secondary as per the John Deere manual, and they are right on both before and after the stumbling conditions occurs. I replaced the fuel line, made sure everything was clean, but like I wrote, when the stumbling occurs it looks like an over-rich condition. Tried loosening then actually replaced the gas cap thinking there may be some type of vapor lock due to the gas cap to no avail. I am usually pretty good with these things but I gotta admit I am about to wit's end with this one. Anyone have any suggestions? Thanks.


#2

Fish

Fish

When it starts stumbling, remove the air filter.


#3

B

bobbwsny

Fish said:
When it starts stumbling, remove the air filter.
Click to expand...

Hello Fish,
Thanks for your response. I did try running it by removing the air filter, made no dif. Still stumbled real bad, so bad I could not use it. Appreciate your input, any other suggestions are appreciated.


#4

wjjones

wjjones

bobbwsny said:
Hello Fish,
Thanks for your response. I did try running it by removing the air filter, made no dif. Still stumbled real bad, so bad I could not use it. Appreciate your input, any other suggestions are appreciated.
Click to expand...



Have you checked, and cleaned the magnet on the flywheel? How are the valves on adjustment?


#5

Fish

Fish

Yes, check the valve adjustment. Here are the specs.

Kawasaki Small Engine Intake and Exhaust Valve Clearances


Did this happen all of the sudden, or did someone have the carb apart? Or someone worked on it? Hit a stump? Etc?


#6

B

bobbwsny

Fish said:
Yes, check the valve adjustment. Here are the specs.

Kawasaki Small Engine Intake and Exhaust Valve Clearances


Did this happen all of the sudden, or did someone have the carb apart? Or someone worked on it? Hit a stump? Etc?
Click to expand...


Thanks for the reply. I will check the valve adjustments. This happened all of a sudden, did not hit anything, did not take carb or anything else apart until I started having this problem.


#7

PJ

PJ

bobbwsny said:
Hello, I have a John Deere 14SE walk behind mower from the mid 90's that I acquired a year ago or so. Can't believe how solid this thing is built, but unfortunatly I can't get the engine, a Kawasaki FC150v, running properly. It starts right up, runs great for about 10 minutes, then starts stumbling. The engine seems to be getting too much fuel, or the electrical system is breaking down. I have had the carb off and apart many times, it is clean, even took the carb to a mower repair shop owned by a friend, they took it apart and could fine no problem with it. The carb and choke linkages are adjusted fine, the carb float seems to be working fine, the needle seems to be seating properly. Have tried many different brands and proper new spark plugs with the same results, they all turn black right away. Tested the OHM resistances in the coil, both primary and secondary as per the John Deere manual, and they are right on both before and after the stumbling conditions occurs. I replaced the fuel line, made sure everything was clean, but like I wrote, when the stumbling occurs it looks like an over-rich condition. Tried loosening then actually replaced the gas cap thinking there may be some type of vapor lock due to the gas cap to no avail. I am usually pretty good with these things but I gotta admit I am about to wit's end with this one. Anyone have any suggestions? Thanks.
Click to expand...


An over rich condition means lack of air to the mixture. I would look and I know you looked at the carburetor. What about the air passage way to the air jet mixture adjustment somehow it is preventing air to get into the mixture air mixture screw turned closed cannot be a big thing have a look

Regards
PJ


#8

R

redfish9

when this happens to my exmark it's most always a bad coil


#9

Fish

Fish

redfish9 said:
when this happens to my exmark it's most always a bad coil
Click to expand...

The coil, or the igniter?


#10

E

Exracer

Fish said:
The coil, or the igniter?
Click to expand...

I'm with Fish since runs fine on start up and takes 10 minutes to fail the coil is suspect if you ask me. They get hot and open causing misfire.


#11

B

bobbwsny

Exracer said:
I'm with Fish since runs fine on start up and takes 10 minutes to fail the coil is suspect if you ask me. They get hot and open causing misfire.
Click to expand...

Appreciate your replies. I checked the OHM resistances in the coil, both primary and secondary as per the John Deere manual, and they are right on both before and after the stumbling conditions occurs. If the coil went bad after getting warm wouldn't these readings not be within range?


#12

Fish

Fish

No, I am with checking the valve gaps first.


#13

E

Exracer

bobbwsny said:
Appreciate your replies. I checked the OHM resistances in the coil, both primary and secondary as per the John Deere manual, and they are right on both before and after the stumbling conditions occurs. If the coil went bad after getting warm wouldn't these readings not be within range?
Click to expand...

I would think yes on the coils after getting hot. The reading would change.


#14

D

dwissinger

I believe it is the ignighter. They short out when they get hot , then work again when cool.


#15

H

Hammerdown

bobbwsny said:
Appreciate your replies. I checked the OHM resistances in the coil, both primary and secondary as per the John Deere manual, and they are right on both before and after the stumbling conditions occurs. If the coil went bad after getting warm wouldn't these readings not be within range?
Click to expand...

Hell Bob
It sure sound's Like and Ignitor Ignition Moduel issue. I happen to have a good one I Pulled off a running engine if you need it let me know I would sell it for $25.00 Plus $5.00 shipping charges. Regards, Hammerdown


#16

E

Exracer

I have found out over the years you can do all the coil resistance test you want and it will not prove if a coil is defective unless it is completely open. The sad truth of this is, a known good coil to try is the only reliable test for a job done right the first time.


#17

primerbulb120

primerbulb120

I had a similar problem on an old Craftsman wheeled weed trimmer. At full throttle, the engine would start, run fine for a few minutes, and then stall as if it had run out of gas. I tried it at half throttle and the problem disappeared. It turned out that one of the passages in the carb was partially restricted. This restricted the amount of gas coming into the float bowl. The gas was not supplied fast enough for the engine to run at full throttle, but there was enough for it to run slowly. This happened after I had repeatedly cleaned the carb. Check the passages leading to the float bowl to make sure they are all clear.


#18

S

SteveHaller

What was the ultimate root cause and resolution of this issue?

bobbwsny said:
Hello,

I have a John Deere 14SE walk behind mower from the mid 90's that I acquired a year ago or so. Can't believe how solid this thing is built, but unfortunatly I can't get the engine, a Kawasaki FC150v, running properly. It starts right up, runs great for about 10 minutes, then starts stumbling. The engine seems to be getting too much fuel, or the electrical system is breaking down. I have had the carb off and apart many times, it is clean, even took the carb to a mower repair shop owned by a friend, they took it apart and could fine no problem with it. The carb and choke linkages are adjusted fine, the carb float seems to be working fine, the needle seems to be seating properly. Have tried many different brands and proper new spark plugs with the same results, they all turn black right away. Tested the OHM resistances in the coil, both primary and secondary as per the John Deere manual, and they are right on both before and after the stumbling conditions occurs. I replaced the fuel line, made sure everything was clean, but like I wrote, when the stumbling occurs it looks like an over-rich condition. Tried loosening then actually replaced the gas cap thinking there may be some type of vapor lock due to the gas cap to no avail. I am usually pretty good with these things but I gotta admit I am about to wit's end with this one. Anyone have any suggestions? Thanks.
Click to expand...


#19

B

bertsmobile1

Exracer said:
I would think yes on the coils after getting hot. The reading would change.
Click to expand...

YOU CAN NOT TEST A MODERN COIL WITH AN INBUILT TRIGGER UNIT WITH AN OHMETER

You can check the secondary windings but if the trigger unit is duff it still will not run.
The minimum gear needed to test it is a rising voltage signal generator & an ossiliscope and they need to be good ones so expect to pay around $ 5,000 to $ 12,000 for them.
OR just replace the coil


#20

B

bertsmobile1

Exracer said:
I have found out over the years you can do all the coil resistance test you want and it will not prove if a coil is defective unless it is completely open. The sad truth of this is, a known good coil to try is the only reliable test for a job done right the first time.
Click to expand...

Correct


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