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All right guys...I need some serious help. The engine spec number is 49623 and its on my Cub 2082. Its original and I dont know how many hours are on it because hour meter doesnt work. It stopped working with ~800 hours on it.

Problem Statement:
Tractor starts fine, runs for 4-7 mins fine, when PTO engaged for mower deck or runs longer the engine continues to heat up the engine starts to stutter (chug/surge) and will then only run with the choke on, then I limp back to the barn.

Diagnosis:
I fingure its either Fuel or Ignition related

Background (what I have done so far):
Fuel:
-Cleaned carb twice, 120psi air, small metal wire, adjusted float, ultrasonic sink, all ports appeared clean and free flowing --> no change in performance
-Checked fuel filter, it is free flowing. I also removed the fuel filter and ran fuel direct to the fuel pump --> no change in performance
-checked fuel shutoff valves - they are both open.
-One remaining item is to check fuel line from tank to fuel filter however when I turned over the engine with the carb removed an adequate amount of fuel from the
fuel line to the carb (which was removed at the time) appeared to be flowing (although I did not measure the flow rate)
-I only run 91 octane (no ethanol) and it is fresh in the tank. Tank appears to be clean
-Purchased new after market carb from iSavetractors.com (nice guy) -->no change in performance
-Disassembled fuel pump, diaphragm is supple, seals are tight, internal check valves are functioning and tight, it is clean
Ignition:
-Plugs are 9 months old, a bit sooty (indicating a rich mixture) but generally clean and gapped properly
-I thought the ingnition module may be going bad so I got (for free) a used one from a local tractor repair man and replaced (what a pain), it is gapped properly at
0.010" -->no change in performance
Other:
-Engine compression test was ~100psi per cylinder, did not do a pressure drop test.

My pride is hurt (insert tear) -- Im going to check the fuel line from the tank to the filter today. I suspect nothing will change. Next step is to check back with the post and see what ideas ya'll might have. Final step is take it to a professional repair shop (this is the hurt pride part) although Im not confident they will fix it.

Of note: I did find a post that described these exact symptoms. A bunch of folks were on the post, in one case there was a clogged fuel line, in one case the carb had an internal plugged port and in one case a guy had a warped head....hoping its not the last.

Any help you can provide would be greatly appreciated.

Nate

Hi Nate. Sounds like this has been driving u nuts for a while. Since pulling the choke out changes the situation....let's start with the fuel. U have been into the carb and it should be clean. Next is filter...and that's clean. Yes....check all fuel lines for clear. My next move might b to rig up a new temperary gravity gas tank if possible. This will help determine if it is the fuel pump. This doesn't sound too safe so if done use extreme care. I'm not familiar with the cyclops fuel tank system. But with the tank in the back under the fender...I'm thinking u really need a good strong fuel pump to deliver. Might b worth buying one for like $50. On the 2072 when the fuel pump stops working...u can fill the gas tank full and get by. I did that for about 6 months.

Fuel!
There are shut offs on both sides of the tank, basically above each tire. They have a screen inside the tank. If your not sure I have had good results pushing a small amount of compressed air through the lines to clean these filters. Be sure to due this with the fill cap OFF the tank, otherwise you will find a weak spot in the rubber line. Been there done that ! Depending on the serial number of your tractor, you could have a mechanical pump or a vacuum pump if it is a mechanical pump (and bad) change to vacuum it will be cheaper in the long run. I prefer to replace all fuel lines when I can, the ethanol in today's gas destroys the old ones. with the fuel line off the fuel pump you should be getting a lot of good flow. (When cranking). If it is getting good flow at this point the issue was the carb It self, clean it again!

+1 on what Joe said, blow back through both fuel inlets at the tank. I've had the same think happen with Cyclops. The screens get clogged with a "silt" that is not very thick. When you you blow back through them you likely won't have to worry about that same stuff clogging them. You have broken the silt up and will likely be ok for years.

Of course it could be some other cause, but start with this! Mine was making me crazy until I figured it out!

I went into the fuel tank on the suggestions above. Im embarrased to say the fix was as simple as blowing out the crap that was stuck in the two shotoff valves attached to the gas tank. I guess the good of it is I know the tractor inside and out now....thanks for the help...shes running nice and cuttin good!

Good news. But don't u mean....Tanks for the help.

Indeed...tanks for all the help!

So....I tore down the engine to do a valve job. I also had an oil leak I couldn't identify so I purchased the M20 gasket kit, which comes with oil seals, from iSaveTractors (that guy is great). Anyway...due to some bad cleanliness practices I believe I have some contaminants in the crankshaft compartment. I do not have new crankshaft bearings. Should I 1. Split the case and thoroughly clean everything or 2. flush the hell out of everything.

Thanks
Nate

Wow....I don't even know what to say....this sounds horrible!
I do like some of I save tractor videos. Seems like a fun guy. He does have new valves for those engines on eBay. I have not seen those valves anywhere else.
As to your question.....i guess I would not risk just trying to flush. What r some symptoms your r experiencing to lead you down this path?
In my mag 20 I installed new bearings just because I wasn't sure of the wear......once I got new in my hand....it did become apparent....old ones looked pretty good. I said....oh well I will never reget installing new. I would tend to think....a year from now...you will not regret tearing it apart and doing what needs done.
Keep us posted

Tore it down all the way. Bearings look good so I will reuse. All oil seals, valves, valve springs and gaskets will be replaced. The compression was good so I'm going to keep the oring (new orings are expensive for this badboy). Ill let you know how it runs when I'm done.

Thanks
Nate

Good! I used oil as my assembly lube...... Tom and Mike think it's all down in the sump by now as it's been about a year and a half since I finished. It's just sitting on the shelf till I get around to installing....

All done, she is back together and sounds much better, runs smoother and starts easier. I put the xtreme motorworks 3 pt hitch on it too....super siked to grade the driveway.

Good to hear!