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Kohler Magnum 16hp runs great and then dies
#1
F
Fescuefreak
F
Fescuefreak
Could use some help. I have an old Walker mower with Kohler Magnum 16 hp that runs great for about 10-15 minutes then starts surging like it is running out of fuel and will backfire as well. If I play with the choke I can limp it along but eventually it dies.
Things I have already done:
1. Replaced the carburetor including new spacer and gaskets
2. Replaced fuel lines just after filter and just after fuel pump (maybe should change fuel line between tank and filter?)
3. Replaced fuel filter
3. Cleaned spark plug and check for spark after engine dies and spark is there
4. Checked and adjusted rpm to 3200 (was previously set to max out at 2700 - pretty far below spec)
5. Replaced batter
6. Replaced voltage regulator/rectifier
These symptoms occur with or without air filter attached and do seem worse or occur more quickly when under load (blades engaged).
After I replaced the carburetor and carb gaskets which were in terrible condition the engine did run a full hour and I completed the mow and thought I had fixed the issue. Then I decided to check the rpm’s and found them to be low at 2700 so adjusted it to 3200 (engine max is 3600) but the symptoms reoccurred during the next mow.
What should I be looking at next? I feel like when the engine gets hot it must be getting too much air in the mixture possibly? Or lack of fuel somehow? Not sure if this old engine even has a safety switch for overheating but I don’t think adjusting the choke would keep the engine alive if that were the issue.
Help appreciated!
Things I have already done:
1. Replaced the carburetor including new spacer and gaskets
2. Replaced fuel lines just after filter and just after fuel pump (maybe should change fuel line between tank and filter?)
3. Replaced fuel filter
3. Cleaned spark plug and check for spark after engine dies and spark is there
4. Checked and adjusted rpm to 3200 (was previously set to max out at 2700 - pretty far below spec)
5. Replaced batter
6. Replaced voltage regulator/rectifier
These symptoms occur with or without air filter attached and do seem worse or occur more quickly when under load (blades engaged).
After I replaced the carburetor and carb gaskets which were in terrible condition the engine did run a full hour and I completed the mow and thought I had fixed the issue. Then I decided to check the rpm’s and found them to be low at 2700 so adjusted it to 3200 (engine max is 3600) but the symptoms reoccurred during the next mow.
What should I be looking at next? I feel like when the engine gets hot it must be getting too much air in the mixture possibly? Or lack of fuel somehow? Not sure if this old engine even has a safety switch for overheating but I don’t think adjusting the choke would keep the engine alive if that were the issue.
Help appreciated!
#2
R
Rivets
R
Rivets
Next time it happens spray everything you can find with carb cleaner, between carb and block. You are looking for an air leak by the gaskets or a crack in the intake manifold opening as it heats up. Also check for debris floating around in the tank.
#3
K
kyledeere79
K
kyledeere79
You should test for a blocked air vent in the gas cap by running your engine til it dies then loosen the cap and listen for air being sucked in. If you do hear the noise of air that means the vent is blocked and causing a vacuum.
The other test I would do is disconnect the fuel line at the carb and crank the engine. Gas should spray out and not just trickle. Obviously don't do that test with a hot engine. If you do need a fuel pump, I recommend getting one from stens or kohler rather than Amaz. The cheapest ones are pretty bad
The other test I would do is disconnect the fuel line at the carb and crank the engine. Gas should spray out and not just trickle. Obviously don't do that test with a hot engine. If you do need a fuel pump, I recommend getting one from stens or kohler rather than Amaz. The cheapest ones are pretty bad
#4
F
Fescuefreak
F
Fescuefreak
Thanks. Will try that. Also, the spacer I installed already had the gaskets attached to the spacer, I did not use any adhesive or anything, just tightened the carb to the intake - is this correct or does something need to be applied to create a better seal?Next time it happens spray everything you can find with carb cleaner, between carb and block. You are looking for an air leak by the gaskets or a crack in the intake manifold opening as it heats up. Also check for debris floating around in the tank.
#5
F
Fescuefreak
F
Fescuefreak
Thanks. I have made sure the gas cap vents… I can push air through it with my mouth so that part is good. I will try testing the fuel pump as you described. Good idea, though don’t know why that would fail once engine gets hot.You should test for a blocked air vent in the gas cap by running your engine til it dies then loosen the cap and listen for air being sucked in. If you do hear the noise of air that means the vent is blocked and causing a vacuum.
The other test I would do is disconnect the fuel line at the carb and crank the engine. Gas should spray out and not just trickle. Obviously don't do that test with a hot engine. If you do need a fuel pump, I recommend getting one from stens or kohler rather than Amaz. The cheapest ones are pretty bad
#6
R
Rivets
R
Rivets
No sealant needed. Hope you got rid of what was on there, because they could cause a leak.
#7
F
Fescuefreak
F
Fescuefreak
Yes, took flat razor blade and carefully removed the buildup without scratching the surfacesNo sealant needed. Hope you got rid of what was on there, because they could cause a leak.
#8
F
Fescuefreak
F
Fescuefreak
Today I decided to tackle some stray grass and bug remnants I saw in the gas tank. At first I tried to fish them out but when that didn’t work I disconnected the fuel line to the tank to let it drain…. Guess what? It only dropped out… like 1 drop every 2 seconds… slow! So I removed the rubber bushing and shut off valve ( it was very clogged with dirt and grass) and ordered a new one. My question is, could this be why the mower runs for 20 min or so and then stops? I could always see fuel in the filter which makes me think this wasn’t the problem (maybe the fuel pump could suck enough fuel out despite the clog?). However, if the amount of fuel the pump could deliver was say 99% percent of demand, the fuel in the carb could last a while being replenished almost as fast as needed but not quite. Parts arrive Tuesday but curious what people’s thoughts are.
#9
R
Rivets
R
Rivets
95% sure you have found your problem. An engine needs far less fuel to run properly, so your full carb at starting was probably clouding your thoughts about how to diagnose the problem. Finally, fuel filter only need to be 25% full for the system to work.
#10
F
Fescuefreak
F
Fescuefreak
I’ll file it under “needed to be done anyway” if it doesn’t fix the issue but hopefully it will. Just not sure how it would run for 20 min after cooling down and supposedly running out of fuel the previous time. How did the carb fill up again to allow another 20 min run time? Maybe idling at startup allowed fuel to fill carb bowl while rpm’s and therefore fuel demand was low?95% sure you have found your problem. An engine needs far less fuel to run properly, so your full carb at starting was probably clouding your thoughts about how to diagnose the problem. Finally, fuel filter only need to be 25% full for the system to work.
#11
B
bertsmobile1
B
bertsmobile1
A very common problem on mowers with low fuel tanks & big filler necks
Yes it is a job that should be done around a 5 year time frame
Worse on ZTR's than Tractor style mowers
Yes it is a job that should be done around a 5 year time frame
Worse on ZTR's than Tractor style mowers
#12
F
Fescuefreak
F
Fescuefreak
The clog in the fuel line at the fuel tank was the issue! Ran the mower for 2 hours with blades engaged and it didn’t think about dying once! Thanks for all the help!
I do have one other question… I’m currently running the engine around 3200 rpms but I’d like to get closer to 3600. The governor screw is all the way out already but I can manually manipulate the throttle (rod?) to increase rpm more. I know not to exceed 3600 but what adjustment do I need to make to get to this 3600 mark?
I do have one other question… I’m currently running the engine around 3200 rpms but I’d like to get closer to 3600. The governor screw is all the way out already but I can manually manipulate the throttle (rod?) to increase rpm more. I know not to exceed 3600 but what adjustment do I need to make to get to this 3600 mark?
#13
grumpyunk
grumpyunk
You did not say what machine the Kohler is installed on. It may not really need a fuel pump when sitting in level ground, and the trickle that got through the fuel outlet and shutoff would fill the float bowl over time.
tom
tom
#14
C
Cajun power
most of wide open throttle and and top rpm is related to a combination of several things, always start with the fundamentals:
1. is the throttle cable moving the governor arm to throttle linkage all the way and that results in the throttle carb valve to open all the way? check all linkages and the damping spring from governor to throttle valve.
2. does the choke valve open all the way and close all the way..?...inspect it and make sure that valve moves freely and the spring is rotating it back to full open rotation when choke is off? if the spring is missing or the choke valve cannot move to the wide open position with choke off, then max rpm will not happen...air fuel mixture becomes too rich. if you take the spring off with ENGINE OFF, the choke valve should open and close all the way back and forth and move freely.
3. quality of fuel? Any possibility of water or old gas? Remove fuel line from carb ENGINE OFF, and check for any contamination or water in the catch container? I use a glass jar...easier to inspect fuel.
4. air cleaner blockage? remove air filter temporarily and see if rpm's go up. If they do, clean air filter or replace.
5. make sure the fuel pump works properly...performing a fuel flow test with the fuel line removed from the carb into a catch container...it should be a good steady flow. If not, check filter and fuel pump.
there is a hidden air needle valve in the carb..usually it's cover by a welch plug. It's factory set and almost never needs to be adjusted. I would leave that alone...clean the carb and remove the bowl and make sure the float and needle valve are clean and the float needle valve has no corrosion on the tip...sometimes it has a little rubber tip...make sure that is not worn down or borked.
while you have the carb bowl off, inspect the anti back fire solenoid ...WITH ENGINE OFF/KEY OFF, you should be able to use your finger to depress the pin into the body of that device. If you cannot depress it by hand, clean that up with carb cleaner or brake cleaner. Then do this...FROM KEY OFF, TURN KEY TO RUN ..NOT START..ONLY TO RUN. You should see the anti back fire solenoid click and retract the pin back into the device and it should stay retracted. TURN KEY FROM RUN BACK TO OFF...pin should pop back out. If the anti back fire solenoid does not operate correctly after cleaning it...consider snipping the pin off entirely...your engine does not really need this device to operate...it's a common problem these devices fail..and that can cause fuel delivery problems. If you are concerned about back fire, move throttle to idle before key off.
and lastly this: kolher engines are manufactured to to meet a lower industry standard than compared to kawasaki. What this means is that engine horsepower (and rpm) are going to vary..because the reality is that the lower standard involves manufacturing quality assurance for each and every engine to be met. As a consequence...a kohler engine "rated" at say 18 horsepower might be only 17 or even 16...whereas a kawasaki engine, factory fresh will always be AT LEAST the rated horsepower because kawasaki manufactures its engines to meet a higher industry standard. This is one of the reasons why kawasaki engines are more expensive that kohler. Kohler because they only meet a certain lower standard means that "rated" rpm may never be possible in any particular individual engine. There is nothing inherently bad about this but it is something to realize when dealing with kohler engines. And it's one of the many factors that has influenced me to only use kawasaki engines in my machines. Not the only factor, but given I would prefer to have 23 horses and nothing less and not have to be concerned about engine performance over time, I stay away from kohler. I have a small side hustle doing mower and machine repairs. It's common to see kohler engines not produce rated rpms. With Kawasaki...that can happen, but it's usually after long hours or when something isn't right with the machine. It's still worth checking the things I listed about with the kohler engine though...just be aware that for every kohler engine, even factory fresh, you may never get rated rpm or rated horsepower. it's just the nature of how they manufacture to a lessor industry standard. still good engines...just not my cup of tea. your mileage may vary
C
Cajun power
first things first..make sure the rpm gauge is accurate. Sometimes they don't work properly or the sensor wire is not attached properly or worn down....verify this if you can with a separate tach meter...they are cheap. But if you don' t have a separate tach meter to verify then skip this and do following to rule out the max rpm issue:The clog in the fuel line at the fuel tank was the issue! Ran the mower for 2 hours with blades engaged and it didn’t think about dying once! Thanks for all the help!
I do have one other question… I’m currently running the engine around 3200 rpms but I’d like to get closer to 3600. The governor screw is all the way out already but I can manually manipulate the throttle (rod?) to increase rpm more. I know not to exceed 3600 but what adjustment do I need to make to get to this 3600 mark?
most of wide open throttle and and top rpm is related to a combination of several things, always start with the fundamentals:
1. is the throttle cable moving the governor arm to throttle linkage all the way and that results in the throttle carb valve to open all the way? check all linkages and the damping spring from governor to throttle valve.
2. does the choke valve open all the way and close all the way..?...inspect it and make sure that valve moves freely and the spring is rotating it back to full open rotation when choke is off? if the spring is missing or the choke valve cannot move to the wide open position with choke off, then max rpm will not happen...air fuel mixture becomes too rich. if you take the spring off with ENGINE OFF, the choke valve should open and close all the way back and forth and move freely.
3. quality of fuel? Any possibility of water or old gas? Remove fuel line from carb ENGINE OFF, and check for any contamination or water in the catch container? I use a glass jar...easier to inspect fuel.
4. air cleaner blockage? remove air filter temporarily and see if rpm's go up. If they do, clean air filter or replace.
5. make sure the fuel pump works properly...performing a fuel flow test with the fuel line removed from the carb into a catch container...it should be a good steady flow. If not, check filter and fuel pump.
there is a hidden air needle valve in the carb..usually it's cover by a welch plug. It's factory set and almost never needs to be adjusted. I would leave that alone...clean the carb and remove the bowl and make sure the float and needle valve are clean and the float needle valve has no corrosion on the tip...sometimes it has a little rubber tip...make sure that is not worn down or borked.
while you have the carb bowl off, inspect the anti back fire solenoid ...WITH ENGINE OFF/KEY OFF, you should be able to use your finger to depress the pin into the body of that device. If you cannot depress it by hand, clean that up with carb cleaner or brake cleaner. Then do this...FROM KEY OFF, TURN KEY TO RUN ..NOT START..ONLY TO RUN. You should see the anti back fire solenoid click and retract the pin back into the device and it should stay retracted. TURN KEY FROM RUN BACK TO OFF...pin should pop back out. If the anti back fire solenoid does not operate correctly after cleaning it...consider snipping the pin off entirely...your engine does not really need this device to operate...it's a common problem these devices fail..and that can cause fuel delivery problems. If you are concerned about back fire, move throttle to idle before key off.
and lastly this: kolher engines are manufactured to to meet a lower industry standard than compared to kawasaki. What this means is that engine horsepower (and rpm) are going to vary..because the reality is that the lower standard involves manufacturing quality assurance for each and every engine to be met. As a consequence...a kohler engine "rated" at say 18 horsepower might be only 17 or even 16...whereas a kawasaki engine, factory fresh will always be AT LEAST the rated horsepower because kawasaki manufactures its engines to meet a higher industry standard. This is one of the reasons why kawasaki engines are more expensive that kohler. Kohler because they only meet a certain lower standard means that "rated" rpm may never be possible in any particular individual engine. There is nothing inherently bad about this but it is something to realize when dealing with kohler engines. And it's one of the many factors that has influenced me to only use kawasaki engines in my machines. Not the only factor, but given I would prefer to have 23 horses and nothing less and not have to be concerned about engine performance over time, I stay away from kohler. I have a small side hustle doing mower and machine repairs. It's common to see kohler engines not produce rated rpms. With Kawasaki...that can happen, but it's usually after long hours or when something isn't right with the machine. It's still worth checking the things I listed about with the kohler engine though...just be aware that for every kohler engine, even factory fresh, you may never get rated rpm or rated horsepower. it's just the nature of how they manufacture to a lessor industry standard. still good engines...just not my cup of tea. your mileage may vary
#15
F
Fescuefreak
I attached a few photos of the pertinent parts. The throttle cable is engaging the spring attached to the governor arm which in turn engages the (carburetor arm?) at the top of the carb… I am wondering if I need to adjust the length of this carb arm (sorry don’t know what to call it) by unscrewing it to make it longer or screwing it in more to make it shorter?
F
Fescuefreak
Thanks for the detailed post! I have a brand new carb so everything carb related should be functioning correctly (in theory). I am using an external tachometer which I tested on another mower (Deere x354) which to my knowledge has never been adjusted and it was reading 3350ish rpms -which sounds like a reasonable number to be factory set to so I am reasonably sure the tach is accurate.first things first..make sure the rpm gauge is accurate. Sometimes they don't work properly or the sensor wire is not attached properly or worn down....verify this if you can with a separate tach meter...they are cheap. But if you don' t have a separate tach meter to verify then skip this and do following to rule out the max rpm issue:
most of wide open throttle and and top rpm is related to a combination of several things, always start with the fundamentals:
1. is the throttle cable moving the governor arm to throttle linkage all the way and that results in the throttle carb valve to open all the way? check all linkages and the damping spring from governor to throttle valve.
2. does the choke valve open all the way and close all the way..?...inspect it and make sure that valve moves freely and the spring is rotating it back to full open rotation when choke is off? if the spring is missing or the choke valve cannot move to the wide open position with choke off, then max rpm will not happen...air fuel mixture becomes too rich. if you take the spring off with ENGINE OFF, the choke valve should open and close all the way back and forth and move freely.
3. quality of fuel? Any possibility of water or old gas? Remove fuel line from carb ENGINE OFF, and check for any contamination or water in the catch container? I use a glass jar...easier to inspect fuel.
4. air cleaner blockage? remove air filter temporarily and see if rpm's go up. If they do, clean air filter or replace.
5. make sure the fuel pump works properly...performing a fuel flow test with the fuel line removed from the carb into a catch container...it should be a good steady flow. If not, check filter and fuel pump.
there is a hidden air needle valve in the carb..usually it's cover by a welch plug. It's factory set and almost never needs to be adjusted. I would leave that alone...clean the carb and remove the bowl and make sure the float and needle valve are clean and the float needle valve has no corrosion on the tip...sometimes it has a little rubber tip...make sure that is not worn down or borked.
while you have the carb bowl off, inspect the anti back fire solenoid ...WITH ENGINE OFF/KEY OFF, you should be able to use your finger to depress the pin into the body of that device. If you cannot depress it by hand, clean that up with carb cleaner or brake cleaner. Then do this...FROM KEY OFF, TURN KEY TO RUN ..NOT START..ONLY TO RUN. You should see the anti back fire solenoid click and retract the pin back into the device and it should stay retracted. TURN KEY FROM RUN BACK TO OFF...pin should pop back out. If the anti back fire solenoid does not operate correctly after cleaning it...consider snipping the pin off entirely...your engine does not really need this device to operate...it's a common problem these devices fail..and that can cause fuel delivery problems. If you are concerned about back fire, move throttle to idle before key off.
and lastly this: kolher engines are manufactured to to meet a lower industry standard than compared to kawasaki. What this means is that engine horsepower (and rpm) are going to vary..because the reality is that the lower standard involves manufacturing quality assurance for each and every engine to be met. As a consequence...a kohler engine "rated" at say 18 horsepower might be only 17 or even 16...whereas a kawasaki engine, factory fresh will always be AT LEAST the rated horsepower because kawasaki manufactures its engines to meet a higher industry standard. This is one of the reasons why kawasaki engines are more expensive that kohler. Kohler because they only meet a certain lower standard means that "rated" rpm may never be possible in any particular individual engine. There is nothing inherently bad about this but it is something to realize when dealing with kohler engines. And it's one of the many factors that has influenced me to only use kawasaki engines in my machines. Not the only factor, but given I would prefer to have 23 horses and nothing less and not have to be concerned about engine performance over time, I stay away from kohler. I have a small side hustle doing mower and machine repairs. It's common to see kohler engines not produce rated rpms. With Kawasaki...that can happen, but it's usually after long hours or when something isn't right with the machine. It's still worth checking the things I listed about with the kohler engine though...just be aware that for every kohler engine, even factory fresh, you may never get rated rpm or rated horsepower. it's just the nature of how they manufacture to a lessor industry standard. still good engines...just not my cup of tea. your mileage may vary
I attached a few photos of the pertinent parts. The throttle cable is engaging the spring attached to the governor arm which in turn engages the (carburetor arm?) at the top of the carb… I am wondering if I need to adjust the length of this carb arm (sorry don’t know what to call it) by unscrewing it to make it longer or screwing it in more to make it shorter?
Attachments
#16
B
bud&dusty
B
bud&dusty
Gas cap not venting.Could use some help. I have an old Walker mower with Kohler Magnum 16 hp that runs great for about 10-15 minutes then starts surging like it is running out of fuel and will backfire as well. If I play with the choke I can limp it along but eventually it dies.
Things I have already done:
1. Replaced the carburetor including new spacer and gaskets
2. Replaced fuel lines just after filter and just after fuel pump (maybe should change fuel line between tank and filter?)
3. Replaced fuel filter
3. Cleaned spark plug and check for spark after engine dies and spark is there
4. Checked and adjusted rpm to 3200 (was previously set to max out at 2700 - pretty far below spec)
5. Replaced batter
6. Replaced voltage regulator/rectifier
These symptoms occur with or without air filter attached and do seem worse or occur more quickly when under load (blades engaged).
After I replaced the carburetor and carb gaskets which were in terrible condition the engine did run a full hour and I completed the mow and thought I had fixed the issue. Then I decided to check the rpm’s and found them to be low at 2700 so adjusted it to 3200 (engine max is 3600) but the symptoms reoccurred during the next mow.
What should I be looking at next? I feel like when the engine gets hot it must be getting too much air in the mixture possibly? Or lack of fuel somehow? Not sure if this old engine even has a safety switch for overheating but I don’t think adjusting the choke would keep the engine alive if that were the issue.
Help appreciated!
#17
S
sessman55
S
sessman55
Check the float levelness. Remove the carb and float bowl. While holding it upside down, the float should be parallel with the mounting surface. If not, the fuel in the carb bowl will deplete faster than it can be replenished. Replace needle and seat to correct this.
#18
S
slomo
S
slomo
If you need more revs, sounds like you need to cut more often or have a lot of rain jacking the grass up. Going any higher to 3600 will only use more fuel. You are over the torque peak anyway.
#19
F
Fescuefreak
F
Fescuefreak
I already solved the fuel supply issue. Just questioning the rpmsGas cap not venting.
#20
F
Fescuefreak
F
Fescuefreak
Interesting. Well, maybe I should just leave it alone. I have no issue with the engine bogging down - I cut often enough. I was just trying to get a cleaner cut by spinning the blades faster and also increasing suction (both by the blower running faster and lift from the blades.If you need more revs, sounds like you need to cut more often or have a lot of rain jacking the grass up. Going any higher to 3600 will only use more fuel. You are over the torque peak anyway.
#21
F
Fescuefreak
F
Fescuefreak
I completely replaced the carb. The issue was a clogged fuel line at the tank connection.Check the float levelness. Remove the carb and float bowl. While holding it upside down, the float should be parallel with the mounting surface. If not, the fuel in the carb bowl will deplete faster than it can be replenished. Replace needle and seat to correct this.
#22
S
stsh709
S
stsh709
Do not buy a fuel pump from Amazon. They don't work.You should test for a blocked air vent in the gas cap by running your engine til it dies then loosen the cap and listen for air being sucked in. If you do hear the noise of air that means the vent is blocked and causing a vacuum.
The other test I would do is disconnect the fuel line at the carb and crank the engine. Gas should spray out and not just trickle. Obviously don't do that test with a hot engine. If you do need a fuel pump, I recommend getting one from stens or kohler rather than Amaz. The cheapest ones are pretty bad