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Cub Cadet RTZ50 Stumbling Under Load

#1

R

rhuba

My 2006 RTX50 (model 17AA5D7P710) with Kawasaki engine has developed a frustrating problem. When the mower is under a load, the engine starts stumbling-cutting out. I noticed that there didn't seem to be any fuel in the filter. I replaced the fuel pump and all the fuel lines after draining and cleaning the tank. Now there is fuel in the filter at all times even when engine is stumbling. I swapped the carburetor with the original, which I had replaced to troubleshoot a hard starting problem. (It didn't fix that issue, so I believe the carb is good.) It seems to run all right unless it is under load. While it is stumbling, there is no evidence of smoke indicating running rich. My next step is to start throwing money at it, ignition modules, etc. I would rather not do that. Anyone run into this problem before? I would appreciate any help.


#2

Scrubcadet10

Scrubcadet10

slowly close the choke when it starts stumbling, see what happens.


#3

B

Bertrrr

Clean the carb


#4

Tiger Small Engine

Tiger Small Engine

My 2006 RTX50 (model 17AA5D7P710) with Kawasaki engine has developed a frustrating problem. When the mower is under a load, the engine starts stumbling-cutting out. I noticed that there didn't seem to be any fuel in the filter. I replaced the fuel pump and all the fuel lines after draining and cleaning the tank. Now there is fuel in the filter at all times even when engine is stumbling. I swapped the carburetor with the original, which I had replaced to troubleshoot a hard starting problem. (It didn't fix that issue, so I believe the carb is good.) It seems to run all right unless it is under load. While it is stumbling, there is no evidence of smoke indicating running rich. My next step is to start throwing money at it, ignition modules, etc. I would rather not do that. Anyone run into this problem before? I would appreciate any help.
Can you describe the “stumble” more specifically?


#5

R

rhuba

Stumbling refers to loss of RPM, sounds like it is going to die, but doesn't completely shut down. I have tried closing the choke and it does die at that point. By removing the load by stopping travel or shutting off mower, it recovers. When I swapped the carb, I assumed that I eliminated the carb as the problem since the original carb didn't have the issue. I will try cleaning when I get the opportunity.


#6

Scrubcadet10

Scrubcadet10

Even though your filter stays full.. next time it starts to stumble, loosen the gas cap, or when you go mow, just start with the fuel cap loose and see if it does it


#7

R

rhuba

I have removed the gas cap and it doesn't have any effect. I have also checked all of the deck pulleys and the mower clutch to make sure there aren't any binding up. The mower clutch is fully engaging and the brake is fully disengaged.


#8

Craftsman Garage

Craftsman Garage

Adjust the valves


#9

StarTech

StarTech

Very possible that the engine is just running on one cylinder. V-twins can run very smooth on one cylinder until under a load.


#10

Craftsman Garage

Craftsman Garage

Yeah, that's happened to me a couple times and I never knew it Iol


#11

R

rhuba

Raining today and just had a tree damaged by hurricane cut down, so I have a couple of days work ahead of me. I will check into the latest tips and update in a few days. Thanks all.


#12

S

slomo

ok has some miles on her.
When the mower is under a load, the engine starts stumbling-cutting out
Typically a main jet is clogged or a dead cylinder if you have two. Make sure you have a solid flow of gas AT the carb inlet.
I swapped the carburetor with the original, which I had replaced to troubleshoot a hard starting problem. (It didn't fix that issue, so I believe the carb is good.)
From 2006, that carb is probably plugged up.
I swapped the carburetor with the original, which I had replaced to troubleshoot a hard starting problem.
So are these carbs OEM Kawasaki parts? Or Chinese Scamazon/Fleabay?
While it is stumbling, there is no evidence of smoke indicating running rich
What do the plugs look like? Put pictures up here so we can see.
My next step is to start throwing money at it, ignition modules, etc.
NO your next step is TEST WHAT YOU HAVE. Here is what you need. Air, fuel, spark "at the right time" and compression.

So you need to check;

1.Pull air filter for TESTING only. See if she will run under load without the filter for a BRIEF PERIOD OF TIME. No change, check air off your list unless the valves are fully out of whack.
2.Pull fuel line AT carb inlet. Drain into a glass jar. Should have a fat steady flow.
3.Pull each plug. Ground them out on a cooling fin or something off the block. You can get those cheap Christmas light kind for each plug. Don't like those myself. Crank engine looking for spark.
4.Pull top engine shroud. Look at flywheel key. Should be in the slot and not stripped out or missing. Take a picture so we can see.
5.Compression test, watch youtube videos if you don't know what to do here.

Good maintenance items are carb, plug cleanings and valve clearance inspections. Clean your cooling fins YEARLY or more often if you bag or scalp.


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